时间状语从句在复合句中起着表达主句动作发生时间的作用，通常要求主句和从句的时态保持一致。以下是关于时间状语从句中常用连词及其用法的说明：
1. when: 表示"在...的时候"，如莫扎特四岁时开始创作音乐：
Mozart started writing music when he was four years old.
2. while: 指"在...期间"，如旅行期间的活动：
He visited a lot of places while he was traveling.
3. as: 用于"在...的同时"或"一边...一边..."，如边走边唱：
We always sing as we walk.
4. after: 表示"在...之后"，如完成作业后的行动：
He left the classroom after he had finished his homework.
5. before: 指"在...之前"，如过去的经历：
Mr. Brown had worked in a bank for a year before he came here.
6. as soon as: 用以连接"一...就..."，强调时间的紧密连接：
We began to work as soon as we got there.
7. since: 用于表示"自从...以来"，尤其是现在完成时和一般过去时的搭配，如持续时间的表达：
Mr. Green has taught in that school since he came to China three years ago.
8. till / until: 表示"直到..."，强调动作的延续，可与完成时态连用：
They walked till/until it was dark.
9. by the time: 到...时为止，引导完成时态的句子：
By the time he gets there, his father has already gone.
理解并熟练运用这些连词，可以帮助你准确地表达时间状语从句，使句子更加丰富和精确。
状语从句 （Adverbial Clause） 状语从句指句子用作状语时，起副词作用的句子。它可以修饰谓语、非谓语动词、定语、状语或整个句子。根据其作用可分为时间、地点、原因、条件、目的、结果、让步、方式和比较等从句。状语从句一般由连词(从属连词)引导，也可以由词组引起。从句位于句首或句中时通常用逗号与主句隔开，位于句尾时可以不用逗号隔开。