How long is it_____ I _____?
A. since…arrivedB. since…has arrivedC. when…arrivedD. as…arrived
答案解析：答案为A .
since英 [sɪns] 美 [sɪns]
prep. 从…以来；自从…之后；自从
adv. 以后，此后；后来；（距今几年）以前；（从那时候起几年）以前
conj. 自从…以来；自从…的时候起；既然；因为
自从； 从； 因为； 以来
So much has changed in the sport since I was a teenager...
自打我十几岁以来，这项运动已经有了很大改变。
Since I have become a mother, the sound of children's voices has lost its charm.
自打我做了母亲后，孩子们的声音就不那么动听了。
...a slight accent she had acquired since he last saw her.
自他最后一次见到她之后，她就有了轻微的口音
不要混淆 for 和 since。
for 用来表示过去、现在或将来的一段时间，还可表示某段时间内某事没有发生：She slept for eight hours (她睡了 8 小时)，
He will be away for three weeks (他将离开 3 周)
I hadn't seen him for four years (我有 4 年没见他了)。
since 用来表示某段时间的起点：She has been with the group since it began
(该集团创建之初她就在那儿工作)
The first civilian president since the coup 17 years ago
17 年前政变后的第一个平民总统
since 还可用来指某事发生的最后时间，或某段时间内某事没有发生：
She hadn't eaten since breakfast (早饭后她一直没吃过东西)
It was a long time since she had been to church
(她很久没去教堂了)。
She's a changed woman since she got that job.
她自从得到了那份工作，变得判若两人。
2. the largest displacement of civilian population since World War Two
自第二次世界大战以来最大规模的平民迁移
3. He's been in the doldrums ever since she left him.
自从她离开他以来，他一直很消沉。
4. Since 1977 otter hunting has been illegal.
捕猎水獭1977年以后就被列为非法了。
5. His quality of life has improved dramatically since the operation.
手术后他的生活质量大大改善了。
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