You'll all have used one at some “stage”of your life already. 这里的stage为什么会是单数呢，人生阶段，应该也可以翻译成 stages of life吧，如果是人生的某一阶段，可前面又怎么有个“some”？
这个句型will have done在这里应该是表猜...
After divided into three groups, all the students set off for the top
of the mountain.问：此题是道改错题，答案是“在divided 前加being, 说after此处为介词，这我能懂。但为什么不能是状语。从句的省略: After (all the students were) divided into three
groups, all...
...子而不是单单的一个动词吧？
例如: She can not dance because of headache. because of
headache因为头疼修饰的是“She can not dance”这个句子吧？If you run, the bear will run too. 如果你跑，那只熊也将会跑。if you run 修饰的是
the bear will run too吧？
The germination rate is low and the time is long, so it maybe have the
mechanism of dormancy.这句话可以把maybe换成may吗？改成The germination rate is low and the time is long, so
it may have the mechanism of dormancy.感觉情态动词在这里也可以用。