He went to buy some fruit.

他去买水果了。（动词不定式作状语。）

He said he would buy some fruit for his sister.

他说他要给妹妹买一些水果。

Xiao Ming:Mike, there's fruit stall up ahead, let's buy some fruit.

小明：麦克，前面有一个水果摊，我们买点儿水果吧。

Xiao Ming: Mike, there's fruit stall up ahead, let's buy some fruit.

小明：麦克，前面有一个水果摊，我们买点儿水果吧。