突出矿井采掘工作面严禁串联通风，在进风侧必须设置至少（）道反风门。A、1 B、2 C、3

已知三角形的三边分别为4，a，8，那么a的取值范围是（　　）

A．4＜a＜8

B．1＜a＜12

C．4＜a＜12

D．4＜a＜6

关于心电图波形的含义，错误的是（）

A.P波为心房除极波

B.Ta波为心房复极波

C.QRS波群为心室除极波

D.T波为心室复极波

E.P-R（Q）间期为心房除极终了至心室除极开始的时间

任务型阅读。

     阅读下列短文,根据所读内容在文章后的表格中填人 恰当的单词。

     注意:表格中的每个空格只填1 个单词.

    The farm economy of the United States has changed a lot in the last seventy years. In the 1930s,

twenty-five percent of the nation's population lived on farms. Today less than one percent of Americans

do.

       Farm incomes have changed over the years, too. For example,in 1933,people living and working on

farms had much less money to spend than other Americans. At that time,farm families had about one-third

the income of non- farmers after all necessary expenses had been paid. By the late  1970s, however, that  difference  had  almost disappeared. In 2004,farmers had their best year ever. The average farm family

earned about eighty-one thousand dollars. That was more than the average American family, which

earned about sixty thousand dollars.

   The Department of Labor measures the pay of industrial workers differently. It measures the average

hourly and weekly pay for industrial workers. This is because factory workers are generally paid by the

hour unlike farmers who earn income from their farm businesses. Generally, the average hourly pay for

all

industrial workers is about sixteen dollars. And the average weekly pay,about five hundred fifty dollars.

     Industrial workers were about twenty-three percent of the labor force in the 1970s. But that number

has been decreasing. Most Americans have jobs that provide services. Professional,technical and other

services employ about eighty-six percent of the labor force.

妊娠期血液成分发生改变，下述哪项是正确的（）

A.血的ESR加快

B.血细胞计数增加，Hb增高

C.纤溶活性增高

D.凝血因子下降

E.白细胞计数增加，以嗜酸性细胞增加为主

某宿舍的内廓为现浇简支在砖墙上的钢筋混凝土平板(图2-6)，板厚 h=80mm，a_s=20mm，板上作用的均布活荷载标准值为q_k=2kN/m²。水磨石地面及细石混凝土垫层共30mm厚(重度为22kN/m³)，板底粉刷白灰砂浆12mm厚(重度为17kN/m³)。

如果改用经调直的550级冷轧带肋钢筋配筋，混凝土强度等级不变，则x（mm）及A_s（mm²）值最接近于（）。

A．8.4；231

B．7.1；216

C．6.3；221

D．5.8；176