在线几道英语选择题!8. The treatment failed ______ his headache. A. to

在线几道英语选择题!
8. The treatment failed ______ his headache.
A. to treat
B. curing
C. treating
D. to cure
11. Air is ______ gases.
A. a mix of
B. a mixture of
C. mixed
D. together mixed
13. Drink ______ water and have a good rest.
A. a plenty of
B. a plenty
C. a number of
D. plenty of
17. I ______ home at five in the afternoon.
A. arrived at
B. arrived
C. reached to
D. got to
18. Your brother’s been to Shanghai, ______ he?
A. has
B. does
C. isn’t
D. hasn’t
请说明其他选项为什么错!