一般木门扇的下风缝(门扇与地面之间)为______mm。
A.2
B.4
C.6
D.8
参考答案:D
--- Jack didn’t come back early last night, did he?
---_____. It was not yet eight o’clock _____ he arrived home.
A.No; before
B.Yes; when
C.Yes; that
D.No; until
飞机的()越大,诱导阻力越小
A.展弦比
B.后弦比
C.中弧曲度