itwasfoundtobeover这里的为啥要加tobe,itwasfoundtobeoverthirteenfeetlong我知道这是被动语态,但是不理解为啥加tobe难道是不定式被动语态所以要加?说的详细一点,

Question

it was found to be over 这里的为啥要加to be,
it was found to be over thirteen feet long 我知道这是被动语态,但是不理解为啥加
to be 难道是不定式被动语态所以要加?
说的详细一点,

Answer 1

句中的to be可加可不加.
还原成主动句就比较容易理解了,如：
I found it (to be) over thirteen feet long.
found是感官动词find的过去式,it为宾语,(to be) over thirteen feet long是宾语补足语.
不定式一般不能做find的宾语补足语,但是to be...可以,且to be一般都可以省略不写.
被动句亦是如此.