船闸的基本尺度是指（）。

A、闸室有效长度

B、闸室有效宽度

C、闸室有效高度

D、门槛最小水深

Springtown’s fire department wants the town council to buy it another ladder truck. These trucks are useful in fighting fires in high-rise buildings. The town council argues, however, that Springtown has only two high-rise buildings, and it already owns enough ladder trucks to fight any fires there. So, they say, Springtown does not need another ladder truck.
The town council’s argument assumes that

A．Springtown cannot afford to buy another ladder truck.

B．Springtown’s high-rise buildings all meet or exceed current fire safety standards.

C．the number of high-rise buildings in Springtown is likely to grow.

D．at least one of Springtown’s ladder trucks is not due to be permanently removed from service in the immediate future.

E．(E) it is possible to fight fires successfully in high-rise buildings without using ladder trucks.