Playing on a frozen sports field sounds like a lot of fun. Isn't it rather risky, ____?

—Are you worried about the coming exam?—Only ______.

David jumped＿＿＿to get the first＿＿＿the beginning of the sports. 

As their memories decline, some old people tend to be talkative because they ______ forget what has just been said.

Faced with the exams, we should work as hard as we can.       , we shouldn’t do it at the cost of our health.