Seven days _____ a long time, I think. [ ]
A. are
B. is
C. an
D. have been
答案：B
In relation to company law, explain:
(a) the doctrine of capital maintenance; (4 marks)
启动远程控制台的电动泵和气动泵，在（）min内应使储能器的液压从7MPa±0.7MPa升至21MPa。
A.10；
B.15；
C.20；
D.25。
