单项选择题

Suddenly he heard someone ______ gently on the window.

A. knock
B. knocking
C. knocked
D. to knock
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Nora hardly (never) misses (an) opportunity (to play) (in) the tennis tournaments.
A. never
B. an
C. to play
D. in
单项选择题
I expected a more enthusiastic welcome, especially () it is the first time I have come here.

A. providing
C. comparing
B. supposing
D. considering
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