It is important to know about the cultural differences that______ cause problems．

Alice, what’s wrong with you? You look so worn out—Nothing seriousI my new house all day and I’m afraid I won’t finish until tomorrow afternoon

______ great fun it is to have a swim on such a hot day!

Do you play basketball

When I _______ in the kitchen, nothing made me feel better than preparing the eggs and serving them just the way the customers wanted.