加速性主要影响飞机的哪些性能（）
A.起飞性
B.复飞性
C.爬升性能
D.舒适性
参考答案：A, B, C
下列操作中，能使电离平衡H2OH+＋OH-，向右移动且溶液呈酸性的是[ ]
A．向水中加入NaHSO4溶液
B．向水中加入Al2(SO4)3固体
C．向水中加入Na2CO3溶液
D．将水加热到100℃，使pH＝6
Frictional unemployment results from:（）
A. inflexible wages in the marketplace.
B. recessionary business conditions and inadequate aggregate demand for labor.
C. constant changes in the economy that prevent qualified unemployed workers from being immediately matched up with existing job openings.
H+＋OH-，向右移动且溶液呈酸性的是[ ]