He was so tired that he fell asleep ___he went to bed.
句意：他是如此的劳累，以至于一躺床上就睡着了。
考查状语从句。as if 好像；even though 即使；ever since 自从；as soon as 一……就……。根据句意及常识，很劳累的人一般是一躺床上就睡着了。故选D。
He was so tired that he fell asleep ___he went to bed.
—Which book do you prefer, Harry Potter or Treasure Island?
—Harry Potter, of course, ____I ___ my sister likes it.
Millie’s research paper isn’t up to standard______ she has worked at it for two weeks.
—Don't forget to protect your eyes well______ you take online classes.
—OK. Thank you, Sir.
_____ the outbreak of COVID-19 is a terrible blow to the country, the government is trying hard to bring the situation under control.
_______ you have problems, just let me know. I'll always be there for you.
We should protect the environment _______ we can make a better world to live in.
____ she is very young, she can take good care of herself.
________ Simon has done well in his studies, he still works really hard.
We will cause less pollution _________we can find ways to reuse or recycle more rubbish.
