I hope ________ a good time on weekends. [ ]
A. to have
B. having
C. have
D. has
答案:A
我国在世界上占有百分比最高的脊椎动物是 [ ]
A.哺乳类
B.鸟类
C.两栖类和爬行类
D.鱼类
灯具的遮光格栅的反射表面应选用难燃材料,其反射系数不应低于( ),遮光角宜为25°~45°。
A.60% B.75% C.70% D.85%