【问】 He calls at every house in the street once a month.(New Concept English，Book 2，L. 6)

[原译]他每月一次到本街来拜访每一户人家。

从译文看call at与call on同义，它们能否互换?

【答】 不能互换。从语法特点上看，call at的宾语是表处所的词，而call on的宾语则是表人的词。从语义上看，call at是指有目的的去某地，通常时间很短，而call on则是指因社交或因公正式访问某人。请对比下列例句：

1. I called at the office as I was passing，but you were out. (LDPV)

我路过时去了你的办公室，但你不在。

2. Our representative will call on you in the course of the next week.

我们的代表将在下周拜访您。

3. In the letter he was asked to call at the station.(New Concept English，Book 2，L.34)那封信要求他去警察局。

请做下面的英语试题：

Shall we call____Mr. Green's house?

A. at B. on C. for D. up