I really want to have a pet dog,_____ my mother disagrees.
A. but B. and C. or D. so
Some people won't realize the importance of their health u________ they lose it.
The story isn't hard to understand, b________ there are no new words in it.
T________ Edison failed many times, he didn't give up and succeeded in the end.
The factory is usually noisy, ________ it is pretty quiet today.
Help others, ________ you'll feel happier.
