He is the only one of the students who ＿＿ a winner of three years.
A. is B. are C. have been D. has
The scientist did ＿＿ experiments to test the new drug.
A. a series of B. a good many of C. a great many D. a lots of
These plants are watered ＿＿ .
A. every a few days B. every third day
C. every others day D. each two days
Guilin is ＿＿ worth ＿＿. Have you been to it?
A. well; visiting B. well; to visit C. very; a visit D. very; a visit
Do you know a lot of research work ＿＿ in recent years?
A. have been carried out B. has carried out
C. are carried out D. has been carried out
My family consider ＿＿ a computer, which is considered ＿＿ a great help in our work.
A. buying; to be B. buying; being C. to buy; being D. to buy; to be
