题目

词语运用 Do you want to be a popular guest who gets invited back? Read our six top【1】(tip) for being a good guest. Clothes—if you are in a formal situation, dress【2】(smart): a suit and tie for men, a skirt and jacket for women. Gifts—if you are going to stay in someone's house, b【3】a small gift if you are staying for a short period of time, a【4】(big) gift for longer periods. Expensive chocolate works in most situations. Don't arrive empty-handed. Greetings—to shake h【5】or to kiss? Wait to see what your host does. Food—always accept it when【6】(offer). Try to 当b＜0时，-ab3=（　　）A．babB．b-abC．-babD．-b-ab