1. Stephen Hawking can’t walk or even speak，_______ he has become very successful.
A. but B. and C. or D. then
2. Write down the phone number, _______ you’ll forget it.
A. so B. and C. but D. or
3. —What was your brother doing at this time yesterday?
—He was reading a magazine _______ I was writing an e-mail at home.
A. as soon as B. after C. until D. while
