【单选题】如图所示,黏性液体沿管道连续稳流。 已知, a , b 两管的截面积相同, c 管的 截面积等于 b 管截面积的一半。 下列说法正确的是:
【简答题】水体污染是指排入水体的污染物的含量超过了水体( ),从而导致水体的物理特征和化学特征发生不良变化,破坏其生态系统。
【单选题】Why did Xiao Wang rent a car in Los Angeles?
A.
Because it was convenient.
B.
Because of the transportation problems.
C.
Because he had much money.
D.
Because it was difficult to find a bus.
【多选题】what are the differences between FOB 、 CFR 、 CIF and FCA 、 CPT 、 CIP ___________
A.
t he way of transportation
B.
place and t ime when the risks are transferred
C.
loading or un loading charges involved
D.
shipping documents involved