[课 下 作 业]
Ⅰ.单项填空
1．Think carefully，________ you will find the answer.
A．and B．or C．for D．but
答案 A [根据句意可知前后句为承接关系，故答案为A项。]
2．________ he has limited technical knowledge，the old worker has a lot of experience.
A．Since B．Unless C．As D．Although
答案 D [前半句提到技术知识有限，后半句则是经验丰富，由此可判断空格处是表示让步关系的连词。]
3．He switched ________ the light and entered the room.
A．in B．to C．of D．on
答案 D [switch on“(用开关)打开”。]
