单项选择题

We must ______ that the experiment is controlled as rigidly as possible.

A. secure
B. ensure
C. assure
D. issue
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单项选择题
The new teacher was very nervous ______ she was well prepared.
A. despite
B. unless
C. even
D. even though
单项选择题
On turning the corner, we saw the road ______ steeply.
A. departing
B. descending
C. decreasing
D. depressing
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