A-A+
It ______ 12 rabbits to test a sample of vacci
问题详情
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
正确答案：B
答案为B。过去曾经需要12 个兔子测试疫苗样本，现在只需要6 个。used to do “曾经”； be used to doing sth．“习惯于做某事”。
