Many children, _____ parents are way working in big cities, are taken good care of in the villages.

I think you should spend as much time as you can_____ Maths and English.

下列各句中，没有语病的一句是（ ）

He was very ill, but now he is out of danger.

The biggest cities in Canada only have about sixmillion people while _______ in China are much larger.