下列关于电子邮件的说法，正确的是______。A．收件人必须有E-mail地址，发件

七、Error correction(短文改错)10分

Coffee houses can be seen anywhere in America.                             1._________

The Europeans brought the idea with them.Soon it                                 2._________

became of their favorite drink.Today people in the                                 3._________

USA drink more coffee than people in any country.                                4._________

They drink them at breakfast,at lunch and between                                 5._________

meal,and not only at home but also at work.Coffee                                6._________

is also drinking around the world.Some people like                                7._________

coffee is very black and very strong.But others like                                8._________

coffee with cream or sugar,or cream and sugar with                               9._________

it.Now coffee has become a world-widely drink.                                    10._________

若有如下程序段，其中s、a、b、c均已定义为整型变量，且a、c均已赋值(c大于0) s=a; for(b=1;b＜=c;b++)s=s+1; 则与上述程序段功能等价的赋值语句是( )。

A．s=a+b;

B．s=a+c;

C．s=s+c;

D．s=b+c;

夜间在明显处所垂直悬挂红、红、白、红灯四盏，则该灯号表示本船没有染疫，请发给入境检疫证。 ( )

试述垂体兴奋试验的意义。

有一种原则是对信息进行均衡、全面的防护，提高整个系统的“安全最低点”的安全性能，该原则称为

A．木桶原则

B．整体原则

C．等级性原则

D．动态化原则