1. The sun, which is a star, provides light and warmth to the earth.

2. She heard a terrible noise, which brought her heart into her mouth.

3. David studies hard and is ready to help others, which is what his parents expect.

4. Tom didn't study hard, which made his mother very angry.

5. Jack drove too fast, which was very dangerous.

在这些例句中，"which"引导的非限制性定语从句提供了关于前面句子或句子部分的额外信息，并且通常用逗号与主句分隔。这些从句可以指代整个主句的内容，或者指代主句中的某个特定部分，如名词、形容词、短语或其他从句。需要注意的是，在非限制性定语从句中，不能使用"that"作为引导词，而应使用"who"、"whom"、"whose"、"as"等词。此外，"which"在从句中可以充当主语、宾语或表语。