_____ you have worked out the first problem, you may go on to work on the second.
Someone called me up in the middle of the night, but they hung up _____ I could answer the phone.
Peter’s mother kept telling him that he should give up smoking, but _____ didn’t help.
It’s quite different from _____ I read last month.
Three-fourths of the homework _____ today.
When you want to write a person’s biography(传记),you must find out _____ about his or her life.