① What will your dad do next week? ____     A. He is a doctor.

② Why do you like summer? ____     B. It is green.

③ What does he do? ____     C. I can see thirteen.

④ Did you have a good time? ____     D. Because I can swim.

⑤ When did you come home?____     E. We’re going to visit the art museum.

⑥ What colour is it?  ____     F. Yes, I enjoyed myself very much.

⑦ What are you going to do tomorrow? ____     G. I did my homework.

⑧ How many cows can you see?  ____     H. At about eleven in the evening.

⑨ What’s Mary doing now?  ____     I. She’s sleeping in bed. She’s ill.

⑩ What did you do last night?   ____     J. He’ll go fishing.

函数$f\left(x\right)=\left(2-x\right)\left|x-6\right|$在$(-\infty ,a$上取得最小值-4，则实数a的集合是（  ）

一实心铜块质量为1.78千克，则铜块的体积为多少？如果把它浸没在水中,受到的浮力为多少?（ρ_铜=8.9×10³千克/米³）