搜题请搜索小程序“爱下问搜题”
问题 选择题
一个袋子中装有4只白球和若干只红球，这些球除颜色外其余均相同，搅匀后，从袋子中随机摸出一个球是红球的概率是
3
4
，则袋中有红球（　　）
A．3只B．6只C．8只D．12只
答案

从袋子中随机摸出一个球是红球的概率是

3
4
，从袋子中随机摸出一个球是白球的概率就是
1
4
，

设袋中有x个红球，据题意得

4
x+4
=
1
4
，解得x=12

∴袋中有红球12个．

故选D．

单项选择题

甲亢患者给以卡比马唑治疗，病情基本控制，药物减量后进入维持阶段，维持期时间一般是( )

A．半年

B．1个月

C．1～15年或更长

D．3个月

E．2个月
查看答案
单项选择题

The history of African—Americans during the past 400 years is traditionally narrated (1) an ongoing struggle against (2) and indifference on the part of the American mainstream, and a struggle (3) as an upward movement is (4) toward ever more justice and opportunity.

Technology in and of (5) is not at fault; it’s much too simple to say that gunpowder or agricultural machinery or fiber optics (6) been the enemy of an (7) group of people. A certain machine is put (8) work in a certain way—the purpose (9) which it was designed. The people who design the machines are not intent on unleashing chaos; they are usually trying to (10) a task more quickly, cleanly, or cheaply, (11) the imperative of innovation and efficiency that has ruled Western civilization (12) the Renaissance.

Mastery of technology is second only (13) money as the true measure of accomplishment in this country, and it is very likely that by (14) this under-representation in the technological realm, and by not questioning and examining the folkways that have (15) it, blacks are allowing. (16) to be kept out of the mainstream once again. This time, however, they will be (17) from the greatest cash engine of the twenty-first century. Inner-city blacks in particular are in danger, and the beautiful suburbs (18) ring the decay of Hartford, shed the past and learn to exist without contemplating or encountering the tragedy of the inner city.

And blacks must change as well. The ways that (19) their ancestors through captivity and coming to freedom have begun to loose their utility. If blacks (20) to survive as full participants in this society, they have to understand what works now.

7（）

A.entirely

B.enter

C.entire

D.entrance
查看答案