28. He is too careful _____ his money; he never buys a drink for us.
Only after the teacher explained it to me a second time _____ the question.
One summer night in 1990, a reporter appeared at the door of Thomas Edison’s laboratory, _____ for an interview.
--- Is Tom still smoking? --- No. By next Saturday he _____ for a whole month without smoking
The traditional goal of science is to discover how things are, not how they ought _____.
In their spare time, they will discuss the _____ to the study of English.