Every possible means_____ been tried，and we find only______ this means can we do it well．

You see, “Food Safety” receives thousands of Internethits a day.—Obviously, it has become one of the _________ topicsrecently.

Mr Zhang is always _______ others. He often gives his seats to someone in need.

My English teacher’shumor was ___make every student burst into laughter.

Only ____ as a volunteer ____ how important it is to grasp English.