16. By the time we found the shelter, some of us _______ sick. *
a.become
b.became
c.have become
d.had become
17. Cultural difference can lead to communication ___________. *
a.success
b.failure
c.breakdown
d.break-up
18. This time tomorrow, I ___________ English. *
a.will learn
b.will be learning
c.learn
d.learned
19. He said he __________ come after dinner. *
a.can
b.will
c.did
d.might
20. Tom asked Mrs Ha where she ______________. *
a.live
b.lives
c.lived
d.has lived