下列反应过程中,同时有离子键和共价键断裂和形成的是( ) A.2H2+O2=2H

题型:选择题

问题:

下列反应过程中,同时有离子键和共价键断裂和形成的是(  )

A.2H2+O2=2H2O

B.NH3+HCl=NH4Cl

C.8NH3+3Cl2=6NH4Cl+N2

D.2Na2O2+2H2O=4NaOH+O2

考点:化学键与化学反应中能量变化的关系
题型:选择题

第3、4咽弓发育障碍导致的原发性免疫缺陷病是()

A.WAS

B.CGD

C.DiGeorgesyndrome

D.CVID

E.SCID

题型:选择题
当x______时,二次根式
x+1
有意义.
题型:选择题

临床上引起水肿的原因有()

A.肝功能损害

B.肾功能损害

C.血浆胶体渗透压下降

D.输入高渗溶液

E.输入人血白蛋白

题型:选择题

阅读理解。

     More surprising, perhaps, than the current difficulties of traditional marriage is the fact that marriage

itself is alive and thriving (兴盛)。As Skolnick notes, Americans are marrying people-relative to

Europeans, more of us marry and we marry at a younger age. Moreover, after a decline in the early 1970s,

the rate of marriage in the United States is now increasing. Even the divorce rate needs to be taken in this

pro-marriage context: some 80percent of divorced individuals remarry. Thus, marriage remains, by far,

the preferred way of life for the vast majority of people in our society.

     What has changed more than marriage is the nuclear family. Twenty-five years ago, the typical American

family consisted of a husband, a wife and two or three children. Now, there are many marriages in which

couples have decided not to have any children. And there are many marriages where at least some of the

children are from the wife's previous marriage, or the husband's, or both. Sometimes these children spend

all their time with one parent from the former marriage; sometimes they are shared between the two former

spouses.

      Thus, one can find the very type of family arrangement. There are marriages without children; marriages

with children from only the present marriage; marriages with full time children from the present marriage and

part time children from former marriages. These are stepfathers, stepmothers, half-brothers, and half-sisters.

It is not all the unusual for a child to have four parents and eight grandparents! There are enormous changes

from the traditional nuclear family. But even so, even in the midst of all this, one thing remains constant: most

Americans spend most of their adult lives married.

1. By calling Americans marrying people the author means that ______.

A. more of Americans, as compared with Eroupeans, prefer marriage and they accept it at a younger ate.

B. Americans expect more out of marriage than Europeans

C. there are more married couples in USA than in Europe

D. Americans are more traditional than Europeans.

2. Which of the following can be presented as the picture of today's American families?

A. A typical American family consists of only a husband and a wife.

B. Many types of family arrangements have become socially acceptable.

C. Americans prefer to have more kids than before.

D. There are no nuclear families any more.

3. Even though great changes have taken place in the structure of American families ______.

A. the functions of marriage remain unchanged

B. most Americans prefer a second marriage

C. the vast majority of Americans still have faith in marriage

D. marriage is still enjoyed by all Americans.

题型:选择题

调整时,工作台上应装有()以上的额定负载进行工作台自动交换运行。

A、50%

B、40%

C、20%

D、10%

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