机翼扰流片的主要作用是()
A.减小阻力
B.减小着陆速度
C.减小机翼升力
参考答案:C
-How are you your classmates?
-Very well. I have made many friends here.
A.getting over
B.getting through
C.getting along with
D.getting on
水磨石若有返浆、杂质的缺陷时,合格品的外观质量缺陷规定:长×宽≤10mm×10mm的缺口不超过( )处。
A.2B.3C.4D.5