Can you hear me?
Can you see me?
Is my video working?
Is my audio working?
for+一段时间
since+一个开始的时间点
for的小笔记：
在肯定句中常常省略for
they've been married( for )ten years.
在否定句中for可以替代成in
they haven't had a holiday in ten years.
不会用for+all
I've lived here all my life.
不是I've lived here for all my life.
今天做两次复健。
等等要做睡前的静心冥想。