代词在句子中用来代替前面已经提到过的人、事物、地点或概念，以避免重复。以下是一些使用指代词的句子示例：

1. 小明买了一本书，他非常喜欢它。

"他"指代"小明"，"它"指代"书"。

2. 我去了超市，那里的商品非常丰富。

"那里"指代"超市"。

3. 老师布置了作业，我们必须按时完成它。

"它"指代"作业"。

4. 这个城市有很多名胜古迹，它们吸引了大量游客。

"它们"指代"名胜古迹"。

5. Tom refused to answer the teacher’s question. This made the teacher angry.

"This"指代前面的一句话："Tom refused to answer the teacher’s question"。

6. Though no one knew it, it would be the last time he would be present at the meeting.

"it"指代前面提到的整个句子："Though no one knew it, it would be the last time he would be present at the meeting"。

7. Ours is a great country. ours=our country.

"ours"是名词性物主代词，指代后面提到的"our country"。

8. He put his hand on mine. mine=my hand.

"mine"是名词性物主代词，指代前面提到的"my hand"。

这些例子展示了代词在句子中如何有效地替代前面提到的名词，使句子更加简洁和清晰。