单选题
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 taking
【正确答案】
B
【答案解析】
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”。
提交答案
关闭