_____ we have built “the Green Wall’, _____we still need to work hard to protect our environment.
--- Let’s go fishing if it _______ this weekend. ---- But nobody knows if it ______.
Simon has spent _____ on his study , but the result of his study isn’t ______.
______ blue clothes _____ good for your mind.
You can stay here , _______ you can leave at once.
.----I’d like a cup of black coffee. What about you, Maggie? --- I prefer coffee______ sugar.