【单选题】三人独立地破译一个密码,他们能单独译出的概率分别为 则此密码被译出的概率为()
【简答题】在正弦交流电中,周期越长.频率越低,交流电变化越慢。
【单选题】The author believes that creativity______
A.
is a unique feature of civilized beings
B.
brings forth the improvement of tools
C.
is the result of human development
D.
helps the advance of culture
【单选题】设三人独立地破译一个密码,他们能单独译出的概率 分别为1/5,1/4,1/3,求此密码被译出的概率.
【单选题】What is an unique feature of horticulture ? _____________
A.
esthetic use of plants
【简答题】在交流电中,电流、电压随时间做___变化,称为正弦交流电;
【单选题】三人独立地破译一个密码,他们能单独译出的概率分别为 1/5 、 1/4 、 1/3 ,则此密码被破译的概率为( ) .
【简答题】Which of the following remains a unique feature of the English countryside? A) Narrow streets lined with pink or white houses. B) Rolling hills with pretty farm buildings. C) Cottages with thatched ro...