16 c 现在分词作定语
17 a
18 a 现在完成时的被动语态
16.Most of the artisis___to the dinner party were from South Africa.
C.invited.
17.Little___that i was never able to see that kind old man again.
D.did i think
18.why haven't you taken the medicine?It ___before dinner.
A.should have been taken
16. d
17. d
18. a