--- How long do you think it is he arrived here? --- No more than half a year, I believe.
6. _________, I attended the meeting instead of him last week.
7. When you read the book, you’d better make a mark ______ you have questions.
8. I didn’t see your sister at the cinema. If she ______, she would have met my brother.
9. _____ all behavior is learned behavior is a basic assumption of social scientists.
10. By the middle of the 21st century , the vast majority of the world’s population ________ in cities rather than in the country.