When did you finish _____ the book last night?
--Now most teenagers write to each other not by letter ________online.--Yes, the Internet has become a part of their life.
--This pair of shoes looks very pretty.--Really! Why not ________?
--Attention please, everybody! Please ________. Mr. Green will begin his report at once.
.-- Is this i-phone _________?--No, it isn’t. I am just thinking of buying________.
The heavy rain stopped the tourists________climbing down the hill.