使用手电钻时应穿().
A.胶鞋
B.凉鞋
C.拖鞋
D.高跟鞋
参考答案:A
We often think of the days ___we spent together on the island.
A.when
B.which
C.in which
D.during which
抗体筛选试验对血标本有何要求?