I.单项选择。（50分）
( ) 1. __ the morning of May, we visited the old man.
A. On B. At C. In D. With
( )2. Most people work ______ the day and sleep ______night.
A. on ; at B. in ; in C. in ; at D. on; on
( )3. Lin speaks English best __ the boy students.
A. between B. with C. on D. among
