The workers in the Huashan Mountains have to rubbish to keep the mountains clean.

Do you know the man ________ is reading the book over there?——— Yes, he is Mr. Green, our P.E. teacher.

Will she ________ go with you? –Well, I’m not sure.

You had better save your time ________.[ ]

On ______ sides of the streets are a lot of colorful flowers.