In America, if friend has invited you to drop in at any time, it is best to call
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In America, if _______ friend has invited you to drop i
n at any time, 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 |
试题答案
C
解析