用句子补全对话。

Black: Hi, Tom. Long time no see!

Tom:  Hi, Black. ____?

Black: Fine. Thanks for asking.

Tom:  It must be a new shirt you're wearing. ____?

Black: It's made of silk. It's very soft.

Tom:  It looks cool. ____?

Black: 100 Yuan.

Tom:  It's not very expensive. I also want to buy one. ____?

Black: I bought it at Xidan.

Tom:  OK! I like blue best.____?

Black: Yes, there is blue shirt at that store.

表示4个氢原子的符号是  （  ）

如果在一片草场上喷洒了某种有毒物质，且这种物质在生物体内难以分解和排出，那么在食物链“草→昆虫→青蛙→蛇”中，体内该有毒物质含量最高的生物是（  ）

有理想，才会有追求。鲜花有理想，才会用美丽装扮大地；蜜蜂有理想，才会用辛劳酿造蜜；____，____。