煤矿井下高压电网,必须限制单相接地电容电流,使之不超过( )A。
A.20
B.15
C.25
D.30
参考答案:A
They enjoyed fresh watermelon last fall because they______ watermelon seeds in the spring.
A.were planting
B.would plant
C.have planted
D.had planted
证券是各类记载并代表一定权益的( )。
A.书面凭证
B.法律凭证
C.收入凭证
D.资本凭证