观察漫画，“向污染宣战”是因为（    ）

①治理污染能彻底解决我国的环境问题                ②目前我国环境问题严峻，形势不容乐观

③治理大气污染是我国生态文明建设的重要一环   ④环境污染严重制约着经济、社会的可持续发展

Boys and girls,

Attention, please! Do you know 1to keep safe in our daily（日常的）life? Today I’d like2 you some ways to keep safe.

1  Always play in a 3 place. A park is a safe place4 there are no cars or buses in it.

2  5 the traffic rules, please! Before crossing a road,6 and look both ways ——look left, look right and look left 7.

3  Never put your head or hands 8 a car, a bus or a train. Many people get 9 or lose their lives by doing so.

4  Don’t 10 a stranger（陌生人）or go with him/her.

That’s all. All the students should obey the rules anytime(任何时候).

如图是分类等级示意图，以下理解正确的是（    ）

点A(x₁，y₁)，B(x₂，y₂)，C(x₃，y₃)都在反比例函数$y=\frac{-3}{x}$的图象上，若x₁＜x₂＜0＜x₃，则y₁，y₂，y₃的大小关系是