【判断题】焊接时,产生和维持电弧燃烧的必要条件是碰撞电离和热电离。
【单选题】当载流子积累的能量 超过禁带宽度 时可使被碰撞的价带电子跃迁到导带,从而产生一对新的电子空穴对,这就是碰撞电离过程,其主要发生在反偏PN结的( )中
【多选题】How to properly ask passengers to turn off mobile phone for take-off?
A.
Could you please switch off your cell phone?
B.
Would you please turn off your mobile phone?
C.
Smoking is not allowed.
D.
Remote-controlled equipment is prohibited.
【判断题】依据客户的性别,年龄等背景因素,可以进行某些变量的假设检验或者方差分析
【判断题】会展职业的核心技能是解决人我国实施进出口商品检验的基本原则和根本目的是为了文化传播。
【多选题】How to ask passengers to turn off mobile phone properly?
A.
Could you please switch off your cell phone?
B.
Would you please turn off your mobile phone?
C.
Would you be kind enough to turn off your mobile telephone?
D.
Excuse me, Miss. For your safety telephone is not allowed to use during the flight.
E.
You can’t use the cellphone.
F.
You mustn’t use your mobile phone.
G.
Please switch off your cell phone.
【简答题】Write some instructions on
how to switch off a laptop
【单选题】进出口商会的基本职能是纽带职能、服务职能和()