问题描述：
这里it is 是指什么,有as.as it is 这种句型吗,请翻译一下句子
The brain is as active during REM sleep---when most vivid dreams occur---as it is when fully awake.
The brain is as active during REM sleep---when most vivid dreams occur---as it is when fully awake.
问题解答：
我来补答展开全文阅读