一﹑单项选择（本大题共20小题，每小题1分，共20分）
在每小题所给的四个选项中，选出可以填入句子空白处的最佳选项，并将答案写在题前的括号内。
( )1. Cathy, put on your coat, or you will have cold.
A. a B. the C. / D. an
( )2. Sam and hurt his leg when he played volleyball yesterday.
A. fell down B. fell in C. fell behind D. fell asleep
( )3. — What happened her?
— She had an accident.
A. with B. to C. of D. about
