call at 后接地点,表示到某人的家或其他场所去拜访某人。
We called at Mr. Johnson's house yesterday. 我们昨天到约翰逊家访问。
I called at his office as I was passing. 我路过时去访问了他的事务所。
call on 比较正式,后接人作宾语,指进行短暂的访问。访问者和受访者一般只有社交或公务关系。如:
They called on us at home. 他们到家来拜访过我们。
We were called on by our neighbours before we had been settled in our new home a week.
我们迁入新居还不到一星期,邻居都来探望过我们了。