在英语选择题中，如何分辨until,since,before,till的用法，举例并给些题目做下，谢谢？

Question

如题所述

Answer 1

since
from a specified event in the past till a later past event,or till now.注意ever since 的用法
瞬间性过去一般时从开始时算起I have lived here ever since you left. 自从你离开后到现在我一直住在这里。It's ten years since I became a teacher. 自从成为教师到现在已经十年了。

延续性过去一般时从结束时算起It's years since I enjoyed myself so much.多少年没这么高兴过了。I have lived here since I was a president.自从我不当总统后一直住在这里。

延续性现在完成时从开始时算起I have lived here since I have been a president. 从当上总统后我一直住在这里。It's five years since I have lived here.自从我住在这里已经5年了。

until（till） up to the time when
主句动词为延续时常用肯定till或until,若为瞬间或位转时常用否定not...until(till)
till 用于口语，但不能用于句首引导从句。until用于句首，从句常用一般 事实时态 。
Wait until(till) the rain stops.
Don't leave till I arrive.
I won't stop shouting until you let me go.
Until she spoke I hadn't realized she was foreign.
I stayed there until (till) she arrived.
I didn't know that until he told me.

before earlier than the time when

免得Do it before you forget.
……就It is not a long time before she came.
宁愿I'd shoot myself before I apologized to him!
才 It was mid-night before she came back.
It'll be a long time before I finish this grammar book.
It may be many years before we meet again.