We shuold collect some rubbish ____the environment .A.to help protect B.help protect C.hel to prot

We shuold collect some rubbish ____the environment .A.to help protect B.help protect C.hel to prot
We shuold collect some rubbish ____the environment .A.to help protect B.help protect C.hel to prot

We shuold collect some rubbish ____the environment .A.to help protect B.help protect C.hel to prot
A.
前面已经有谓语should了
BC两答案都又加上help做谓语
而一个句子里只能有一个谓语
因此只能用不定式to do结构 在此表目的