完成下列句子。

1. 不久以后第一个工人联盟形成了.

It was not _____ ______ the first workers' league ______ ______ ______.

2. 我们应该对中国人口老龄化问题引起注意,它对整个社会产生很大影响.

We should _____ our ______ to the aging population in China, which will _____ a

great ______ ______ the whole society.

3. 他总是很守信用,可到现在他却不见人影.

He always _____ _____ ______, but he hasn't ______ _______ so far.

4. 有些学生假装知道了他们不知道的东西.这是有害的.

There are some students ______ _____ _____ _____ what they don't really know, which is _____ to them.