肺结构和功能的基本单位是 [ ] A．肺泡 B．肺部毛细血管 C．细支气管 D．

如抽样结果有95%的可信赖程度，则抽样结果有5%的可容忍误差。()

More than 6000 children were expelled(开除) from US schools last year for bringing guns and bombs to school, the US Department of Education said on May 8.

The department gave a report on the expulsions as saying handguns accounted for 58 percent of the 6093 expulsions in 1996—1997, against 7 percent for rifles(步枪) or shotguns and 35 percent for other types of firearms.

"The report is a clear sign that our nation’s public schools are cracking down(严惩)on students who bring guns to school", Education Secretary Richard Riey said in a statement, "We need to be tough-minded(坚强的) about keeping guns out of our schools and do everything to keep our children safe. "

In March 1997, an 11-year-old boy and a 13-year-old using handguns and rifles shot dead four children and a teacher at a school in Jonesboro, Arkansas. In October, two were killed and seven wounded in a shooting at a Mississippian school. Two months later, a 14-year-old boy killed three high school students and wounded five in Daducab, Kentucky.

"Most of the expulsions(开除), 56 percent, were from high schools, which have students from about age 13, 34 percent were from junior high schools and 9 percent were from elementary schools. " The report said.

The report from the US Department of Education shows that（）.

A．the number of the expulsions is now large

B．the number of the expulsions is wrong

C．there are soldiers hiding among the students

D．guns are out of control in US schools

国际收支平衡表包括哪些账户和项目？它们之间有什么关系？

液压装卸臂回转接头内密封检查，发现孔内有（），必须更换密封圈。

A.输送的介质

B.润滑油

C.润滑脂

D.没有油

脂溶性药物在体内通过生物膜的方式是（）

A.主动转运

B.简单扩散

C.易化扩散

D.膜孔滤过

E.离子通道转运