It's our duty to make a contribution to______(protect) the environment. 括号中应填什么形式?为什么?

it's our duty to protect our environment/是什么意思请问 it's our duty to help ____(protect)the environment it's our duty to fight___this kind of terrible disease. It's our duty to ____ _____ _______（保护环境） it's our duty ti distribute to the society it's our duty ti distribute to the society...翻译下.. It's on duty to keep our classroom clean 改为同义句_______ ________ our classroom clean is our duty. Waste paper should be throun every were,It's our duty to keep our city clean I think it's our duty to keep our environment clean and tidy. It's our duty to make our city much_____A.dirty B.clean C.dirtier D.cleaner Don't t_____ here and there.It's our duty to keep our school clean it is our duty to do It's our duty to save all the people's lives here.如何翻译? It's our duty to help b___ people because they aren't able to see. It's our duty to help (b ) people because they aren't able to see it's our duty to get the work ----- A to finish B finishCfinishing Dfinished We ought to protect environment. It's our duty to do that. 翻译 关于如何保护我们的水源以it's our duty to save water 为题 It's our duty to keep the balance of （n ）以n开头的词