In America, if ______ friend has invited you to drop by anytime, it is ______ best to call before visiting to make sure it is convenient for him.
A.a; a
B.the; a
C.a; 不填
D.the; 不填
网友回答
C解析考查冠词：前面泛指任何一个朋友，后一空为固定句式it’s best to do sth最好做..,best是形容词，前面不要冠词，句意是：在美国，如果一个朋友要请你随时拜访他，最好事先打个电话确认他是不是方便。选C