Everyone should help save the planet. — Yeah. I’ve stopped ______ plastic bags when shopping.

_____ do you talk to your teacher at the School of the Air?—Once a week.[ ]

Although he failed this time, he didn’t give up and ＿＿＿＿＿＿studying hard.

This is my first trip ______ Beijing. [ ]

____ one-hour documentary takes ____ close look at the life of giant pandas in Wolong.