Life is like an onion，sometimes makes you weepwhen you try to open it

How did you work out the difficult chemistryproblem— I worked it out by ________.

Mark isn’t coming to the concert _____ he has finished his work.

I can’tfind my Mp5, but it must be inmy bedroom.

Every time she was in trouble, she went to him for help, as he said he ___ do anything for her