1.主谓
Last week I went to the theatre
谓语动词went。
to the theatre是一个介词短语，表示”地点、方位”。所以词句并不是主谓宾结构。
另外，如果一个动词后面加介词的（went to），往往就意味着这个动词不及物。
2.主谓宾
I had a ... good seat.
我有一个座位，典型的“主谓宾”结构，谓语had。
3.主系表
The paly was ... interesting.
be动词was
简单句一共分5类，其实最常用的就是上面这3类：主谓、主谓宾、主系表。
4.
I did not enjoy it.
did not enjoy算一个谓语动词，所以词句是主谓宾结构。
还原成动词原形：I enjoy it.
5.
A ... man and a ... woman were sitting behind me
were sitting是过去进行时，是一个时态，所以算一个谓语动词。
behind me是一介词短语。所以词句是主谓结构
