Having lived in China for 8 years, Helen has a good ______ of both English and Chinese.
He heard a loud noise, and it sounded __________ a train had been going under his house.
—It's late. I have got to leave now. —OK. __________
We should think carefully about _____ Mr Needham said at the meeting.
These events are _____ to each other.
When you visit France, it is a _____ if you cannot speak French.