If there ___ peace,we must try in every way to prevent the w

We must try our best to prevent the lake from pollution. We must try our best to d( ) more (说 ) every minute if we wa 英语填介词问题We must aim ___ world peace in the long term. at present there must be nothing we can do to prevent the ju We must wear special boots to prevent us___-in the air. we must take some measures to prevent the environment being we must try our best to prevent tht flu from spread ____ a h the way to prevent littering We must try our best to helo the people___danger.___里要填什么词.（ We must go there ___ the piano. The idea ___ ______,but we need to try it ___ in practice.这个 we tired to ask him to try out his new idea and in the end w