问题
选择题
A variety of butterflies ________ flying in the jungle, one of which is a very rare one.[ ]
A. is
B. have been
C. are
D. has been
答案
答案：C
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A variety of butterflies ________ flying in the jungle, one of which is a very rare one.[ ]
A. is
B. have been
C. are
D. has been
答案：C
____ (clean) three times a day.