---May I remind you that Mr. White is waiting outside, Mrs. Green? ---Oh, I _________ all about it.
I didn’t see your sister at the cinema. If she ______, she would have met my brother.
____ all behavior is learned behavior is a basic assumption of social scientists.
By the middle of the 21st century , the vast majority of the world’s population ________ in cities rather than in the country.
It is because people are likely to stay indoors ______ the virus can spread easily ______ people often catch colds.
He gave us a nod and muttered a “yes” after _______ seemed like hours.