第2题: [单项选择]You had better ______ a doctor as soon as possible. A. seeing B. saw C. see D. seen 参考答案:C 答案解析:[解析] had better (had best)do sth:最好做某事;had better(had best)not do sth:最好不要做某事。例如:You had better not
第17题: [单项选择]The accumulation of air and other non-condensable gases in a refrigeration system will (). A. cause a loss of the liquid seal B. create a vapor lock in the liquid receiver C. collect in the condenser D. cause foaming of the oil in the crankcase 参考答案:C