【简答题】共发射极基本放大电路如图 1 所示。计已知三极管的β =100 , U CC =12V , R B =500k Ω, R C =3k Ω, R L =6k Ω,算 ( 1 )静态工作点 Q ; ( 2 )计算电压放大倍数 ,输入电阻 R i ,输出电阻 R o ; ( 3 )求放大电路不接负载时的电压放大倍数。 图 1
【单选题】One natural disaster that frequents America are _____, which can hit anywhere along the Gulf Coast or the Atlantic Coast as well as Hawaii in the Pacific Ocean.
【单选题】听力原文: The decade for natural disaster reduction is a program designed to reduce the impact of natural disasters throughout the world. With support from the United Nations, countries will be encouraged...
A.
To predict natural disasters that can cause vast destruction.
B.
To limit the destruction that natural disasters may cause.
C.
To gain financial support from the United Nations.
D.
To propose measures to hold back natural disasters.
【单选题】Choose the correct answer to replace the underlined words. Our answer will be threatened by one natural disaster after another if we don't act now.