A. loose soil B. keep soil in position C. harden soil D. Both A and B 参考答案:D 答案解析:[解析]由“...break the soil up-allowing the rain to sink in—and also bind the soil”可知树木的两种作用:loose soil
第21题: [单项选择]斜管沉淀池液面负荷为5m3/(m2·h),六角形斜管的内切圆直径为30mm,倾斜角度为60°,斜管的壁厚不计,则弗劳德数为______。 A. 2.7×10-5 B. 3.5×10-5 C. 2.9×10-5 D. 3.9×10-5 参考答案:B 答案解析:V=Q/(A'×sin60°)≈Q/(A×sin60°)=5÷0.87-5.75(m/h)=0.0016(m/s)(因此题条件所限,无法求出A',故用清水区面积A代替A') R=D/4=0.
第24题: [单项选择]Where did the conversation most probably take place A. In a library. B. In a classroom. C. In a bookstore. D. In a park. 参考答案:C 答案解析:[听力原文] M: I would like to have a copy of Professor Robert Stam’s book on theatrical aesthetics, p