长方体或正方体( )个面的总面积,叫做它的表面积。
6
—Is the result of the experiment satisfactory?
—No, _____.
Which is wrong? [ ]
A. not a bit
B. by all means
C. by no means
D. not in the least
航空器在飞行中,若需改变高度层时,通常情况下机长应()
A.决定后立即改变;
B.主动与空军管制部门联系,经其同意后方可改变;
C.经有关空管部门许可后方可改变