“Everyone thinks of changing the world, _______ no one thinks of changing himself.” A famous Russian writer once said.

We have been good friends __________ we joined the music club.
A. before           B. since             C. until

I don’t have to introduce him to you ________ you know the boy..

Listen carefully, _______ you can’t hear what the teacher is saying.

______ you say sorry to your uncle, he won’t forgive you.

---Would you like to go bike riding with us tomorrow?  ---Sure, ____ I am busy.

Before the show I practiced a lot _________ I could do well at the show.

— It’s time to go to bed, Mary.
— Oh, Mum, I won’t go to bed _____ I have finished my homework.

– Can I watch TV now, Mum?
– No, you can’t watch ______ you finish your homework.
A. as                           B. after                        C. until

--- Did you call the police?  --- Yes, I called them _________ I saw the accident.
A. before                 B. as soon as                 C. until