'Bob' 是句子 'Bob threw the ball' 的主语。

'Bob' is the ___subject of the sentence 'Bob threw the ball'.

在句子 'She enjoys reading books' 中，'She' 是主语。

In the sentence 'She enjoys reading books', '___She' is the subject.

句子 'The cat is sleeping on the sofa' 的主语是 'The cat'。

The ___subject of the sentence 'The cat is sleeping on the sofa' is 'The cat'.