call sb和call sb at有什么不同？

call on与call at都表示"拜访"，两者区别在于后面所接宾语的不同。

call on后面接somebody，而call at后面接some place。 

1、I called on him yesterday.我昨天拜访了他。 

2、I called at his house yesterday.我昨天拜访了他家。 

此外，call on/upon还可以表示"号召"，构成词组call on/upon somebody to do something "号召某人做某事"。 

We are called on to make some personal decisions every day.每天我们被号召去做一些个人决定。