The sunspot came into its active stage last year,        that happens once every eleven years.

Haze (雾霾)appears around us. Let’s do ________ helpful to protect the environment.

We have been looking at houses, but haven’t found _____ we like yet.

Shanghai is larger than_________in Jiangsu, and it is larger than_________ in China.

The best job is ____which uses your skill in doing something with your interest in the subject.