1.
Null pointer always compares equal to the constant zero.
空指针不同与任何类型指针，空指针同于“值为0的常量”，空指针不同于“值为0的变量”。
2.
(of time)for leisure;unoccupied
（指时间）空闲的,未占用的
3.
of fields or open country.
指田地或空旷的地区。
4.
aeromarine radiobeacon
海空两用无线电指向标
5.
direction-giving beacon
【航空, 航海】指向信标
6.
Dampness, especially of the air.
湿度湿度，尤指空气湿度
7.
Air Force Materiel Command
美国空军军需品指挥部
8.
space tracking laser beacon
空间激光跟踪指向标
9.
SACCS (Strategic Air Command Control System)
战略空军指挥控制系统
10.
aero obstruction light
航空碍航指示灯航空障碍灯标
11.
The influence of pointing distance and pointing mode on the choice of spatial demonstratives
指别距离和指别方式对空间指示语选择的影响
12.
The church tower stood against the sky like a finger pointing towards heaven.
教堂的塔像指向天空的手指，在天空的衬托下看得清清楚楚。
13.
Command Transmission and Control of Air Brake in the Combined Brake of Air and Electricity
空电联合制动中空气制动的指令传输与控制
14.
A designated sector of space, such as that in the vicinity of an airport.
航空区一个指定的空间区域，如机场邻近地区
15.
Photographic aerial reconnaissance especially of military targets.
空中照相侦察空中照相侦察，尤指军事目的的
16.
Ballistics, especially of missiles, in the atmosphere.
空气弹道学特指导弹在空气中的弹道学
17.
The Theory of Empty Categories and the Identification of Empty Categories in Chinese;
空语类理论和汉语空语类的辨识与指称研究
18.
Place and seat(both countable)are used for specific spaces,usually for people to sit
place 和seat（均为可数名词）指具体的空处,通常指座位