With a year to go before the UK leaves the EU, there are plenty of questions about Brexit still unanswered.
As negotiators continue to hammer out the details of the withdrawal agreement and start to outline the future relationship, many are wondering what will change and what will stay the same.
Here are some of the questions posed by the BBC audience.
I do not wish to be robbed of my European citizenship. I feel more European than British. Can I keep my citizenship?
Mrs T Conlin, Loddon, Norfolk
The short answer is no. As I'm sure you know, there's no such thing as an EU passport and you are an EU citizen only because you have a passport from one of the 28 member states.
In effect your UK passport gives you a number of rights and guarantees, including the ability to move freely between EU countries to work, live or study.
But if, as expected, the UK leaves the EU on schedule on 29 March 2019, it will then become "a third country". At that point you'd no longer be a citizen of an EU country and consequently no longer an EU citizen.
Things won't change much for a while because the UK and the EU have reached agreement in principle that there should be a transition period between 29 March 2019 and 31 December 2020 during which all EU law will continue to apply in the UK. That would mean that you'd enjoy exactly the same rights and guarantees as before.
But a word of warning on the transition (or implementation period as the government prefers to call it): it is part of the overall withdrawal agreement and will come into effect only if the withdrawal agreement is ratified by both the EU and the UK before Brexit day.
The uncertainty around citizens' rights has led to tens of thousands more UK citizens applying for citizenship in other EU countries in the 12 months after the Brexit vote than in the previous year, according to data obtained by the BBC last year. But not everyone has the right (through family links or residency) to do that.
Can't we leave any sooner?
Martin Buchan via Twitter
In theory we could leave tomorrow if Parliament simply repealed the European Communities Act, the legislation that took us in to the EU (or the EEC as it then was) in the first place.
But that isn't going to happen. First of all it would probably put the UK in breach of both EU and international law. Secondly, the government doesn't want to leave straight away and neither do the vast majority of MPs.
Why not? Because that would take us off the "cliff edge" that you may have heard about. Leaving without any withdrawal agreement in place, and no discussion of the future trade or security relationship, would be the hardest of hard Brexits.
Don't forget, we've been in the EU for 45 years, and untangling that relationship is incredibly complicated. That's why many people describe what's going on at the moment as the most complex negotiation in modern history.
A "cliff edge" Brexit - without any new structures to replace the old EU ones - could in the short term see no flights between the EU and the UK, lorries and people stuck at border crossings, imports and exports of food rotting at the border and huge delays in the movement of vital supplies such as medicines, not to mention the impact on restaurants, manufacturing, tourism and other sectors. Chaos, in other words.
So is no deal really better than a bad deal?
There are those who argue that no deal would be the worst deal of all. The rhetoric is all part of the give and take of negotiation, of course, and the government wants to make the process of withdrawal as smooth as possible.
That is why it has also agreed in principle to a transition (or implementation) period for 21 months after Brexit to give more time to get all those new structures in place.
What will happen to the MEPs from the UK when the UK leaves the EU, and how much UK taxpayers' money will be saved by not having any MEPs?
Michael Jones, Swindon
As soon as the UK leaves the EU, the 73 UK MEPs who were elected by UK voters will lose their seats. That means there will no longer be any UK representation in the European Parliament, even during the transition period after Brexit, when the UK will still have to follow all EU rules and regulations.
All MEPs are paid out of the EU budget, rather than from their national budgets. So in that sense there'll be no direct saving to the UK taxpayer when the UK MEPs leave - but obviously the UK pays its share of the EU budget.
Once the transition period is over, at the end of 2020, the UK will pay only for specific things and the salaries of MEPs will not be one of them.
Bearing all that in mind, here is a quick calculation. The current gross salary for an MEP is €8,611 per month. So, the total gross cost of all UK MEP salaries (at current exchange rates) is just over £6.6m per year. But MEPs also get substantial allowances for staff and travel and office costs, so the total saving will be considerably higher.
It's also worth pointing out that all MEPs who stand down or lose their seats are entitled to a payment of one month's salary for each year they served, to a maximum of 24 months. If an MEP takes a mandate in another parliament or another public office, or if he or she retires, they are not entitled to this payment.
Two current UK MEPs have already served for more than 24 years - David Martin (Labour) and James Nicholson (Ulster Unionist Party). Among those who will have served for nearly 20 years by the time the UK is due to leave the EU next year are arch-Brexiteers Nigel Farage (UKIP) and Daniel Hannan (Conservative).
It is not clear at this stage who will meet these severance payments for departing UK MEPs: the UK government or the EU. This is yet another detail that has to be decided before 29 March 2019.
And in terms of overall savings, remember the UK will be paying into EU pension pots, including the one for MEPs, for many years to come.
Can we still do the EuroMillions lottery?
Nigel Patrick via Twitter
Yes, you will still be able to play the EuroMillions lottery and Brexit will not affect that. The bad news is that Brexit is highly unlikely to increase your chances of winning.
EuroMillions might sound like it is run by the EU or by the countries that use the euro, but it has nothing to do with either.
The game is based on an agreement between the official lottery operators of nine countries, one of which - Switzerland - is not a member of the EU. The eight EU countries are: Austria, Belgium, France, Republic of Ireland, Luxembourg, Portugal, Spain and the UK (for now).
What will happen to British citizens' right to study in Europe for cheaper fees or free?
Those rights will certainly change, but they may not disappear entirely.
Currently, any British student can study at a university in any EU member state, provided he or she fulfils the entry requirements of that institution. The rules also say that all EU nationals are entitled to use a host country's education system on the same terms as its own nationals.
So a British student will pay the same tuition fees as the national of that country or no fee at all, if that's the case for the home students there.
(By the way, the fact that students from England, Wales and Northern Ireland have to pay more than students from elsewhere in the EU to study in Scotland is down to devolved UK law, it's nothing to do with the EU.)
But back to the question itself: the UK and the EU have agreed in principle that any UK citizen who moves to study in another EU country before Brexit (due to happen on 29 March 2019), as well as during the transition period after Brexit (due to run until the end of 2020), will retain the right to study on the same terms as that country's own nationals.
Again that assumes that the withdrawal agreement is implemented and the transition goes ahead. And it's worth bearing in mind that as long as you start your course before the transition ends, you will still pay local rates even if your course continues after the transition is over.
What about those who want to start studying in the EU after the transition - in 2021 and beyond? Well, that is likely to depend on the policy that each individual country has on tuition fees for non-EU students.
Germany, for example, abolished university fees in 2014, and all students - German, EU or non-EU - can study there for free or for a small fee that mainly covers administration costs.
So you are likely to be able to study on exactly the same terms in Germany, unless Germany decides to change its own domestic law. But in some other countries the opportunity to take advantage of cheaper tuition fees will no longer be available.
Are we going to lose our free mobile roaming when in the EU after Brexit?
Ghene Snowdon via Twitter
We could well lose free mobile roaming, but it is hard to give a definitive answer at this stage.
If the UK leaves the EU on 29 March 2019 with a withdrawal agreement in place, then it won't happen immediately. All EU rules and regulations, including on free mobile roaming anywhere in the EU, will continue to apply until the end of the transition period, on 31 December 2020.
It's also possible that the transition period could be extended, but that's fairly speculative at this stage.
So what will happen to free mobile roaming once the transition period is over?
Well at that point, EU laws will no longer apply to the UK and UK mobile network operators will be able to reintroduce roaming charges if they so wish. Some major operators say they currently have no plans to do so, but that can't be guaranteed and it's bound to be affected by the commercial decisions taken at the time by both EU and UK operators.
It's also possible that the UK government could create its own laws regulating roaming fees after Brexit. But we don't know if it would, and even if it did any such law would probably have to take the form of an agreement with the EU. In other words, it would depend on a future UK-EU future trade deal that has yet to be negotiated.
We never talk about the economy of scale created by the EU. How much would it cost for the UK to duplicate all the EU agencies?
Stephane Caussin, London
There has been no estimate published for the overall cost of replacing EU agencies and it would be difficult to come up with one. But it won't be cheap.
There are dozens of EU agencies that the UK currently relies upon, regulating everything from aviation and maritime safety, through chemicals and pharmaceuticals, to food and drink.
Some people might say we don't need them, it's all just excessive bureaucracy. But without regulations on airline safety your planes can't take off, and without regulations on pharmaceuticals you can't buy and sell medicines. So it does matter.
Building new institutions from scratch, training staff and developing expertise, will take considerable time and money.
For example, ADS - the lobby group for the aerospace industry - estimates that replacing the work the European Aviation Safety Agency (EASA) does in the UK would cost about £400m over 10 years.
But one reason why it's hard to say how much money could be spent overall on new regulators is that the UK government doesn't want to duplicate the work of all EU agencies. It says it would like to continue to participate in some of them after Brexit and it is prepared to pay the EU for that.
In fact, in her Mansion House speech earlier this month, Prime Minister Theresa May said EASA was one the agencies the UK wanted to remain part of. Two others she mentioned were the European Medicines Agency and the European Chemicals Agency. Full UK membership is not on the cards, so the UK wants to explore some form of associate membership.
The trouble is that for many people in the EU that looks like another form of UK cherry-picking. It also raises questions about the role of the European Court of Justice in overseeing EU agencies. The UK hopes such doubts can be overcome, but it all remains to be negotiated.
One of the arguments made by supporters of Brexit is that they want to be free to regulate some things in a different way - to meet the needs of an economy that is changing fast. But it will certainly cost plenty of money to set up a new system.
Update 5 April 2018: this article has been updated to reflect the fact that leaving the EU straight away would probably put the UK in breach of EU and international law.