His father cooks
She (often) helps him
Your watch looks very nice
I'll show you my photos /I‘ll show my photos to you 
At first I found Chinese hard
There is an apple on the desk


这六个句子分别显示出了一个句子结构

主谓

主谓宾

主系表

主谓双宾

主谓宾补
前五个我都知道,但最后一个应该是什么?
是there be 还是主谓状?如果是主谓状,那么状语是什么,是什么状语?