初中英语六大句型及其例句如下：

简单句（Simple Sentence）

例句：She runs every morning.

并列句（Compound Sentence）

例句：I like ice cream, but I don't like chocolate.

复合句（Complex Sentence）

例句：Although it was raining, they still went for a walk.

复合-复杂句（Compound-Complex Sentence）

例句：I went to the store to buy groceries, but I forgot to bring my wallet, so I had to borrow money from my friend.

祈使句（Imperative Sentence）

例句：Turn off the lights before leaving the room.

疑问句（Interrogative Sentence）

例句：What time is the train leaving？

这些句型构成了初中英语语法的基础，掌握这些句型有助于提高英语写作和口语表达能力。建议通过大量的练习和实际应用来巩固这些句型。