选择题：It ______ 12 rabbits to test a sample of vaccine, now it takes only 6.

题目内容：

It ______ 12 rabbits to test a sample of vaccine, now it takes only 6.

A. used to taking

B. used to take

C. is used to take

D. was used to

参考答案：

According to the passage, it is true that ________. in the late 19th century in

According to the passage, it is true that ________.in the late 19th century in the United States the

分类：习题答案题型：选择题

able better toable to betterbetter to ablebetter able to

分类：习题答案题型：选择题

The purpose of non-REM sleep is even more mysterious. The new experiments, such as those _____ for th

分类：习题答案题型：选择题

请选择(14)处最佳答案（）。A．spreadB．interferenceC．exclusionD．influence

分类：习题答案题型：选择题

Stressful environments lead to unhealthy behaviors such as poor eating habits, which ________ increas

分类：习题答案题型：选择题