高等继续教育 / 英语阅读II
正确率：100%
It is desireable that the airplane ＿＿＿＿＿ as light as possible.
A、is
B、were
C、believed to be unlikely
D、had been
A、is
B、were
C、believed to be unlikely
D、had been
参考答案：