10大污染物质中最危险的一种是()
A、铅
B、汞
C、辐射
D、二氧化硫
参考答案:C
选词填空 。
1. What would you like (with, for) breakfast?
2. She and he (doesn't, don't) like eggs.
3. What would you like, cabbage (and, or) onion?
4. The fish (is, are) too salty.
5. I (can, would) like some carrots.
6. I'm very (full, hungry). I like to eat some eggs.
常见的网络拓扑结构有星型、环型、【 】和树型等几种。