A heavy learning burden leads to unhealthy behaviors such as poor eating habits, which ___ damage the health of students.
Only after he had spent several nights working on the math problem _______ to wonder whether the problem was wrongly set.
__________ David could remember, he had never said an angry word to that customer.
________ enthusiasm when he heard our advice, he didn’t take any notice.
You must have waited here for a long time, __________?
Although a teenager, Fred could resist ______ what to do and what not to do.