Try your best to help the people when they are in trouble, _______you will feel pleased and happy.
By looking at a problem in as many ways as possible, creative thinkers can find solutions that would _______ remain invisible.
—What has made him upset recently? —_______ alone to face a troublesome milk case.
When he realized the police had spotted him, the man _______the exit as quickly as possible.
—Where is Tom? —Well, he______ you_______ here.Otherwise he would come down right now.
Our bad living habits will destroy the earth.Only by changing ______ we live can we save the earth.