问题
选择题
I'm going fishing after I finish ________ my homework . [ ]
A. to do
B. to doing
C. doing
答案
答案:C
I'm going fishing after I finish ________ my homework . [ ]
A. to do
B. to doing
C. doing
答案:C
下表是几种常见的元素:
元素名称 | 钠 | 铁 | 铝 | 氢 | 氯 | 氧 | 硫 |
(2)2个氢原子表示为______;保持水的化学性质的微粒是______.
(3)下列原子结构示意图中,表示金属原子的是______(填序号).