在电路计算中,电流的参考方向通常是()。
A、任意选定的;
B、由正极指向负极;
C、由负极指向正极;
D、与实际的电流方向一致。
参考答案:A
根据句子的意思,补全单词。
1. I want to have an _____ house for my big family.
2. The boy always plays the _____ to get attention.
3. The manager fired an old _____ yesterday.
4. She went to the _____ to sell what she had made yesterday.
5. You won't see live animals in a _____.
分别燃烧下列各组物质中的两种有机化合物,所得CO2 和H2O的物质的量之比相同的有[ ]
A.乙烯、丁二烯(C4H6)
B.乙醇、乙醚(C2H5-O-C2H5)
C.苯、苯酚
D.醋酸、葡萄糖