Don't know if this is a pun on the word 都 with though, or you actually want to know why 都 is used in this sentence. xD
You don't have to use 都. I think in this case it adds emphasis.
In a previous grammar section it is explained that 每 。。。 都 translates to "every single one". But this is usually not accepted as a correct answer. Very inconsistent.
What's the difference between "every year" and "every single year"? What's your exact grievance?
I'd also like to know why 都 is used. Does it go with 每年?
Yes, if you use "mei", quite often follows "dou". It's kind of an emphasis.
Why not "switches"?
All of the Chinese lessons are so poor and inflexible!
This man must be very handsome and romantic.
Which one do you prefer? Be a single person or change girlfriends every year?
I prefer to be a single person to save my money
Yes it gets rather expensive if you buy a new girlfriend every year
"He changes girlfriend every year" 'non-plural' should also be accepted (by Duo, not by his girlfriends)
It should be either his girlfriend or girlfriends. Your non-plural sounds wrong to me, but I'm not exactly the best english speaker.
sorry, I'm a native English speaker, and it is not correct to say "he changes girlfriend" (non-plural). It must be plural. AndrewKang4 is correct
I dont think so, even though this was funny