---I’m sorry, but there is no smoking on this flight.---Oh, I _____that. Sorry, I won’t again.A. don’t know B didn’t know C. won’t know D. haven’t known
Noise is unpleasant, _____ when you are trying to sleep.
So hard-working _____ that he sets a good example to all the other classmates.
With more and more forests _____, many animals are facing the danger of dying out.
As we all know, China is a developing country, _____ attracting more and more foreigners.
The beautiful town, _____ we spent our summer vacation last year , lies at the foot of a mountain.