1.It's difficult to warn people about them.提醒人们注意它们是很困难的。
It's +形容词+to do sth.意为“做某事怎么样”。
2.Usually people have little or no idea about what to doduring an earthquake.通常人们在地震时不知道该做什么。
3.If you are in a bus or car,stay in it.如果你在公共汽车上或者车上，就待在里面。

根据汉语意思完成句子

1.我们没有机会赢这场比赛。
we have no chance to win the match.

2学生们正在为考试做准备。
The students are preparing for the test.

3.远离火灾。
Stay awayfrom fire.

4.停止说话，该上课了。
It's time for class. Stop_ talking .