1. My mother used to tell me stories _________ I went to bed.
A. since B. until C. before
2. You’d beter take the keys _________ I’m out.
A. in case B. since C. after
3. My brother likes eating fried chicken _________ it’s very bad for his health.
A. because B. although C. when
4. Yesterday, Jim was playing the piano _________ his sister was playing the flute.
A. as B. although C. while
5. You shouldn't spend too much time on computer _________ it is harmful to your eyes.
A. as B. when C. although