在备考英语四级时，语法是必须重点关注的部分，掌握语法规则将显著提升我们的语言运用能力。新东方在线整理了2025年12月英语四级语法知识：since的四种用法，供各位考生参考。
2025年12月英语四级语法知识：since的四种用法
1) since +过去一个时间点 (如具体的年、月、日期、钟点、1980, last month, half past six)。
I have been here since 1989.
2) since +一段时间+ ago
I have been here since five months ago.
3) since +从句
Great changes have taken place since you left.
Considerable time has elapsed since we have been here.
4) It is +一段时间+ since从句
It is two years since I became a postgraduate student.
以上就是新东方在线英语四级频道为大家整理的“2025年12月英语四级语法知识：since的四种用法”，希望大家能够更好的掌握英语四级语法攻略，提高英语四级水平。