---What is that? Is it an English learning machine?---Yes. It ________ us to improve our English.A. is used for helping B. used to help C. used to helping
—How many birds can you see in the trees? —I can see _________ birds in them.
A dog robot could help ____ the room.
—Where is Miss Wang? —She went to Hainan Island last week and will return _________ six days.
There will be ____ cars and ____ pollution twenty years later.
—What is a resolution?—It’s