They offered courses _________ students know the importance of protecting the Huanghe River．（ ）
A．helpB．helpedC．helpsD．to help
The toys are really old，_____I still want to keep them．（ ）
A．orB．andC．but
We should brush our_____every day．（ ）
A．toothB．teethC．hand
Yuan Longping is very creative． We all look up to_____．（ ）
A．itB．himC．her
We can't see_____sun at night．（ ）
A．aB．anC．the
A lot of trees ____________ every spring in Yiyang city． （ ）
A．plantB．is planted
C．are planted