1.Mary has receied several e-mails from her mum since she__t

1.Mary has receied several e-mails from her mum since she__to China.
A came B comes C has come D will come
2.Your friends have ___smoked before ,have they?
A just B ever C never D yet
3.When i got home,i saw him ___on the internet.
A working B was working C work D worked