周恩来提出求同存异方针的重要国际会议是（    ）

⑴Are you going to the beach?____         A. I'm going to the shop.

⑵Where are you going?____                   B. Yes, I am.

⑶Is he going to the bank?____               C. She is going to the park

⑷Where's she going? ____                      D. No，he isn't.

⑸What's Jenny doing?____                     E. She's thinking

下列代数式中：3+a；$\frac{1}{x}$；0；﹣a；-$\frac{5xy}{3}$；$\frac{x+2}{4}$；3x²﹣2x+1；a²﹣b²；a²b²．

单项式：____ 

多项式：____ 

整式：____ 

如上右图是某昆虫的发育过程示意图，请据图回答问题：