This is _____ useful book. I've read it for ______ hour.
A. an, /
B. an, an
C. a, an
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The girl _____ an English song in the next room is Tom's sister.
A. who is singing
B. is singing
C. was singing
Here is your bill. Please______(check) it carefully.
The luggage ___ (leave) at the air port by a careless traveller.
The sauna is on _____(two) floor.
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