一、单项选择（共15小题，每小题1分，计15分）
( ) 1. Einstein，the famous scientist，was born ____________ March，1879.
A. at B. on C. in D. to
( ) 2.--why not _____ to the park now?
--Good idea ! Let’s go.
A. go B. to go C. goes D. going
( ) 3. You won’t pass your exams_____ you work harder.
A. when B. if C. unless D. after
