题目

Although Mr. Jenkins wanted to buy a new computer as quickly as possible, he decided to____ to see where he could find the best deal. A . sink or swim B . push your luck C . burn the midnight oil D . shop around 答案：D常言道，水火不相容，但用透明冰块磨制成一个光学器件，却可以取火．这块用冰磨制成的光学器件相当于下面的A.平面镜B.凸透镜C.凹透镜D.近视眼眼睛片