When do elephants form. into a group？
A. When they are feeding the young.
B. When they see a familiar elephant.
C. When they are giving birth to baby elephants.
D. When the leading elephant gives out a warning.
查看答案
【B15】
A. perfect
B. successful
C. badly
D. well
You don't need to introduce her. I ______ her several times this year.
A. had met
B. have met
C. met
D. meet
The experiment is well worth ______ again.
A. trying
B. being tried
C. to try
D. to be tried
We learn in geography that the valley surrounding the Yangtze River is one of ______ fertile in China.
A. the most
B. the more
C. most
D. a most
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