What are you reading, Jim—I’m not really reading, just _____ thepages.

下列各句中没有语病的一项是（ ）

It is easy to ________the differences between them because they have little ____.

_____ the city’s public school system should be open to the children of migrant workers has become the focus of discussion.

Mr. Hu, can you tell us how to learn swimming well—Sure. But remember we can learn nothing well _______ hard work.