对于任意向量$\overrightarrow{a},\overrightarrow{b},\overrightarrow{c}$、下列命题中正确的是（   ）

①乒乓球队原有15个乒乓球．

②又买来30盒．

③每盒6个．

问题1：____

问题2：____

用方框所给出选项完成对话。

Polly: Dad, I want to get a job.

Father : ____ 

Polly: I need money. When I go out with my friends, I never have enough money.

Father: Polly, you know most families here are richer than we are.

Polly: ____  Then, I won't have to ask you for money.

Father: You have a lot of homework everyday. How can you work and study at the same time?

Polly: ____

Father: I have an idea. Once a week, you can come to my shop and help out a bit. You can clean the floors and the windows－that sort of thing. I’ll pay you for each hour you work. How does that sound?

Polly: ____  But I don't want to clean any toilets(卫生间).

Father: ____  It's a deal.

在下面一段文字横线处补写恰当的语句，使整段文字语意完整连贯，内容贴切，逻辑严密。每处不超过20个字。

    中国要发展还是要环保？几十年来，①____，相伴随的则是环境破坏触目惊心。官方一直宣传要“经济与环境一把抓”，而事实证明，②____。那么，我们有没有可能痛下决心，③____？在经济放缓带来的弊端与环境恶化带来的弊端之间，想好到底承受哪一个了吗？