试一试: Woman: You're really good at tennis! Man: Thanks. I've played ___ ten years. 选出那个男人会说的话。 (since / for / at) 答案: for — ten years 说的是多久，所以用 for。
since + 从什么时候开始
since 后面接从什么时候开始：since Monday，since 2020。
It's been cold since Sunday.
试一试: Man: Do you want to go to bed? Woman: Yes. I've been up ___ five o'clock. 选出那位女士会说的话。 (for / at / since) 答案: since — five o'clock 是开始的时间，所以用 since。
How long have you …?：你……多久了？
问到现在为止有多久，就说 How long have you + 过去分词 … ?
How long have you known her?
试一试: Man: ___ have you been a nurse? Woman: For five years. 选出那个男人会说的话。 (How long / How much / When) 答案: How long — 她回答的是多久，所以他问的是 How long。
该用 for 还是 since？
说持续多久，用 for；说从什么时候开始，用 since。
for two weeks · since last Tuesday
试一试: Man: Sorry I'm late! Woman: That's okay. I've only been here ___ a few minutes. 选出那位女士会说的话。 (ago / for / since) 答案: for — a few minutes 说的是多久，所以用 for。