The girl at the back of the room laughed.这里面谁是主语?前提问过,the girl,但是书本和老师都说是 the girl at the back of the room.理由如下：There are a number of tests to demonstrate that the sequence 'the young girl at the ba

The girl at the back of the room laughed.这里面谁是主语?前提问过,the girl,但是书本和老师都说是 the girl at the back of the room.理由如下：There are a number of tests to demonstrate that the sequence 'the young girl at the ba
The girl at the back of the room laughed.这里面谁是主语?
前提问过,the girl,但是书本和老师都说是 the girl at the back of the room.
理由如下：
There are a number of tests to demonstrate that the sequence 'the young girl at the back of the room' behaves as a single unit (an NP):
1.Pronoun substitution - She laughed (where she=the young girl at the back of the room; comapre with She at the back of the room laughed)
2.Yes/no question - Did the young girl at the back of the room laugh?(where the whole sequence has to be between the aux.did and the main verb laugh; compare with Did the young girl laugh at the back of the room?- which has a different meaning).
To address your second point,the PP 'at the back of the room' modifies the noun 'girl' and in this sense it functions like an adjective.（这是在邮件中对我下面提问的回复）
提问：As i read the handout,here is an example of a sentence,'The young girl at the back of the room laughed'.
the explanation siad; the subject of this sentence is not just "the young girl' but the whloe sequence' the yong girl at the back of the room'
then i got a question.
1 why is that?
2 'at the back of the room' is the attributive,is it?
因此,

The girl at the back of the room laughed.这里面谁是主语?前提问过,the girl,但是书本和老师都说是 the girl at the back of the room.理由如下：There are a number of tests to demonstrate that the sequence 'the young girl at the ba
1. the subject is the young girl at the back of the room because she did the laughing.
2. at the back of the noun is preposition phrase describing the girl, it tells the reader that it is the young girl at the back of the room, not just any girl in the room