The scientist has failed in the test 100 times.He is trying () 101st time.A a B an C the D 不填
问题描述：
The scientist has failed in the test 100 times.He is trying () 101st time.A a B an C the D 不填
答
A 这位科学家在实验中失败了100次.他正在进行又一次尝试.这里在序数词前+不定冠词表示“再,又”.