-- May I smoke here?-- If you____, that's the smoking section over there.
—What do you think I should wear for such a formal press conference? —Dress _______ you like.
Radium salts,which have been found to ______ in bones,give rise to bone cancer.
Our teacher insisted that the key words worth paying attention _______ before class.
With some technical problems to be solved, it may be a while _______ the system is put into use.
That is the only way we can imagine _______ the overuse of water in students’ bathrooms.