find it adj for sb to do和find it is adj for sb to do sth区别

一个主句中不可以有两个谓语动词,若选C 则found和is同为动词,这是双谓语的错误.而且find it impossible to do sth是固定短语
另外,宾语从句的that不可省略,所以如果一定要用is 那应该将其转化为宾语从句的形式he found that it is impossible to get there on time.