气源系统为下列哪个飞机系统提供高压空气（）
A、空调
B、水箱增压
C、机翼防冰
D、以上全部
参考答案：D
—Was it there you were away to see your friend off ?
—I’m not sure . But when I got back , it was gone .
A．that
B．which
C．while
D．where
字母“Q”的ASCII 码值是十进制数
A．75
B．81
C．97
D．134
