We won’t give up ______ we should fail 10 times.
It was in the street where a serious accident happened last week ______another happened yesterday.
We all know that a bright future will ______those who always look ahead instead of looking back.
We ________the difficulty together, but why didn’t you tell me?
He gave the old couple a lot of money and didn’t expect to receive anything ______for them.
The math problem seems very easy, but in fact it is very difficult_______.