sometimes he found ( ) very hard to work fo a long time because many visitors came to his home .

问题描述:

sometimes he found ( ) very hard to work fo a long time because many visitors came to his home .
A it B it's
为什么

这是find+宾语+补语结构,it为宾语.
find后并非从句,若选it's则有find和is两个谓语