若一个扇形的面积是12π，它的弧长是4π，则它的半径是（ ）。

When the little ugly duck grew _____, it grew _____ a beautiful swan. [ ]

A. up; up          

B. up; into          

C. into; into          

D. into; with

AT的抗凝血酶活性在下列何种因素的作用下达2000倍以上（）

A.肝素

B.VitK

C.血栓调节蛋白

D.蛋白S

E.以上都不是

观察意外死亡在不同年份的变化趋势，宜选择的图形为（）。

A.直方图

B.直条图

C.圆图

D.普通线图

E.统计地图

Students who date in middle school have significantly worse study skills. They are four times more likely to drop out of school and report twice as much alcohol and tobacco use as their single classmates, according to new research from the University of Georgia.

"Romantic relationships are a trademark of adolescence, but very few studies have examined how adolescents differ in the development of these relationships," said Pamela Orpinas, study author and professor in the College of Public Health and head of the Department of Health Promotion and Behavior.

Orpinas followed a group of 624 students over a seven-year period from 6th to 12th grade.

Each year, the group of students completed a survey indicating whether they had dated and reported the frequency of different behaviors, including the use of drugs and alcohol. Their teachers completed questionnaires about the students’ academic efforts. He found some students never or hardly ever reported dating from middle to high school, and these students had consistently the best study skills according to their teachers. Other students dated infrequently in middle school but increased the frequency of dating in high school.

"At all points in time, teachers rated the students who reported the lowest frequency of dating as having the best study skills and the students with the highest dating as having the worst study skills,” according to the journal article. Study skills refer to behaviors that lead to academic success such as doing work for extra credit being well organized, finishing homework, working hard and reading assigned chapters.

"Dating a classmate may have the same emotional complications of dating a co-worker," Orpinas said, "When the couple break up, they have to continue to see each other in class and perhaps witness the ex-partner dating someone else. It is reasonable to think this could be linked to depression and divert attention from studying.”

“Dating should not be considered a ceremony of growth in middle school,” Orpinas concluded.

小题1:According to the passage, students who date in middle school may_____

A．have poorer academic performances

B．be more likely to hurl others

C．enjoy better school lives

D．are less likely to use alcohol and tobacco小题2:When doing his study, Orpinas_____.

A．followed a group of students of 6th and 12th grade

B．completed a survey and a report each year

C．completed questionnaires about the students’ academic efforts

D．found that the students’ study skills have connection with their frequency of dating小题3:Study skills may include the following behaviors and qualities Except_____

A．being diligent

B．being well organized

C． being kind and helpful

D．finishing assigned schoolwork小题4:What can possibly happen to the school couples after they break up?

A．They don’t want to see each other any longer.

B．Their attention to studying will be affected.

C．They will miss their ex-partners sometimes

D．They will think it reasonable to get depressed.小题5:Orpinas’ attitude towards dating in middle school is_____

A．supportive

B．positive

C．negative

D．indifferent