根据句意,用所给动词的适当形式填空。

根据句意,用所给动词的适当形式填空。
小题1: The teacher told us that the earth (travel) around the sun.
小题2: Trees and grass play an important part in _______ (help) improve our environment．
小题3: Many trees___________(plant) in my hometown every year.
小题4: CCTV is starting a project _________( call ) “Looking for the most beautiful country teachers.”
小题5: We are talking about where ___________(spend ) our coming winter holiday.