She _____ to take her book two hours ago.
A. returned
B. returns
C. returning
D. return
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Mary and Rose enjoyed _____ when they went skiing yesterday.
A. herself
B. yourselves
C. themselves
D. yourself
I went to Beijing _____ my parents.
A. and
B. to
C. also
D. with
Mark is very funny and often makes us laugh into _____ .
A. sick
B. tears
C. face
D. smile
抗生素类药物的活性采用()来表示
A. 百分含量
B. 标示量百分含量
C. 效价单位
D. 浓度