【单选题】把电动势为1.5V的干电池正极直接接到一个硅二极管的正极,干电池的负极直接接到一个硅二极管的负极,则该管
【简答题】石灰岩的主要矿物成分是( ) A石英 B方解石 C白云石 D长石
【单选题】He has heard from his elder brother.
A.
has received his elder brother’s letter
B.
has heard of the news of his elder brother
C.
has bought a gift for his elder brother
【单选题】'His brother is teacher'______ He has a brother'.
【判断题】预付账款和应收账款都是资产项目,他们可以互换使用。