Without the ‘ greenhouse effect’, the earth be about thirty-three degrees Celsius cooler than it is.
A. should
B. would
C. will
D. must
网友回答
A. should
(答案→)B. would
C. will
D. must
解析：考查虚拟语气中的情态动词。本题是一个虚拟语气，条件是通过介词without（要不是…如果没有…）体现出来的，句意：要不是“温室效应”的影响，地球的温度会比现在要低30华氏度。CD两项不能用与虚拟语气。本句的would表示会；should表示应该；故B正确。