基尔霍夫第一定律又称为节点电流定律，其表达式是（）。
A.∑U＝0
B.∑TR＝∑E
C.∑I＝0
D.I=U/R
参考答案：C
根据句意及首字母或汉语意思完成句子。
1. What's your o________ of Mr. Li?
2. Everyone should show his t________ when he gets into the hall.
3. I saw the White House today. The P________ of the USA lives there.
4. He can speak ________ (外国的) language, such as English, French.
5. We sent a card with birthday ________. (问候)
地壳-地幔之间如何进行物质循环？
