读一读，填一填，补全对话。
Ms Smart: Lingling, look at your bag! It's __1__. You can't take it to China. I'll __2__ you a new one.
Lingling: Thank you.
(At the department store)
Lingling: This black bag is nice. It's 3 !
Ms Smart: But it's 4 . This green one is 5 . And it's got two _ 6__.
Lingling: But it's small.
Ms Smart: Look _ 7__ this blue one. It's big and light.
Lingling: Oh, yes!
Sales assistant: And it's got four 8 . It'1l be 9 for you.
Ms Smart: Great ! We'll take it, please.
Lingling: Thank _10__ very much.
抛出一个质量为m的小球，小球落地前瞬间的速度大小为
，不计空气阻力和人的高度，人对小球做的功为( )
-mgh
-mgh