【单选题】The explosive range of a mixture of flammable vapors is specified as a percentage of _____.
A.
flammable vapor by volume in air
B.
oxygen present to support combustion
C.
the temperature of the flash point
D.
the lower limit of explosibility of the mixture
【单选题】He is so angry that he can't take control___his feelings
【多选题】DRA单板描述正确的是()
A.
因为DRA单板噪声系数小,那么可以完全替代采用EDFA技术的OA
B.
DRA在应用时,输入口连接的光纤也是其实现放大功能的一部分
C.
在DWDM系统应用中,通常都是DRA+EDFA配合使用
D.
在工程中使用DRA板要特别注意:上电开泵前,务必在信号输入端接入40km以上的光纤,并且不得在上电后拔其IN口光纤
【单选题】The man is too old, and he can't take care of himself. He has to _____ his sons. [ ]
【简答题】除Co和Al外,几乎所有合金元素都使Ms及Mf点下降,因此淬火后相同含碳量的合金钢比碳钢的残留奥氏体量 。
【单选题】Which statement is TRUE concerning fuel vapors on a vessel().
A.
Fuel vapors gather in the lowest portions of the vessel
B.
Fuel vapors can only be ignited by an open flame
C.
Vent outlets should be located above the level of the carburetor air intake
【单选题】安全环保检测线的技术检验分为人工检验和__________两大部分。
【单选题】He can't take ________.