下列由血管因素引起的紫癜是A．过敏性紫癜 B．血友病 C．血管性血友病 D．DIC

用括号内所给动词的适当形式填空，必要时可加助动词或情态动词。

       One day when the famous American scientist Edison _____ (walk) on his way home, a young man

stopped him and required ______ (have) a word with him. Edison _____ (accept) his request.

       The young man asked, "How, Mr. Edison, _____ you _____ (invent) so many things and achieve

your fame?"

        The scientist said, "It seems that you have been thinking of ______ (become) famous every day."

        The young man nodded, "Yes, I _____ (be) dreaming of being a person as famous as you. Every

minute I _____ (think) of you how to become reputable. I don't know when I can achieve my fame."

        Edison told him, "Don't worry, young man. If you want _____ (be) a famous man this way, you

_____ (have) to wait until you _____ (die)!"

        "Why should I?" the young man was _____ (puzzle).

         Edison said, "What you dreamed is actually a high building. You never think of how _____ (build)

it with bricks. Thus the building will never come into reality. However, your story _____ (serve) as a

mirror. You _____ (remember) because of your idleness and laziness. They will often speak of your name

while they_____ (give) warnings to their children. Aren't you a notorious person by then?"

        The young man _____ (feel) very shameful and said, "I knew I ______ (not work) hard before, but

I'll build my building."

已知醋酸达到电离平衡后，改变某条件使电离平衡向正反应方向移动了，则下列说法正确的是（　　）

A．醋酸的电离程度一定增大

B．发生电离的分子总数增多

C．溶液的pH一定减小

D．溶液的导电能力一定变强

投保人指定受益人时须经（）同意。

A.保险人

B.监护人

C.被保险人

D.受益人

为观察某草药对致癌物毒性拮抗作用，将60只大鼠随机分三组，每组20只进行毒性实验，对照组发生肿瘤为0只，致癌物组发生肿瘤为15只，草药+致癌物组发生肿瘤为8只。

自由度为（）

A.1

B.5

C.3

D.60

E.59

在Visual FoxPro中，属于域完整性的范畴的定义是

A．数据类型

B．数据模型

C．关系模型

D．关系模式