牙周炎的主要病理变化之一是（） A.牙松动 B.菌斑形成 C.牙龈增生 D.牙龈出血

用四环素族类药物可致恒牙发生四环素牙的时期是

A．胚胎4个月

B．胚胎6个月

C．出生以前

D．7岁以前

E．8岁以后

Bored? Don't know what to do with your time? Get your friends or family together, go to the park or go hiking, do something fun —just don't turn on your TV.

The 10th annual TV-Turnoff Week starts on Monday. The TV-Turnoff Network, a nonprofit organization, began the program in 1994 to get children and adults to watch less television so that their time is spent doing more productive things. This year, millions of people will participate and find much more interesting things to do besides sitting in front of the television.

Experts are convinced（确信）that watching too much TV keeps kids from participating in healthy physical activities. The average household has a television on for 7 hours and 40 minutes a day! Kids spend more time watching TV than they spend in school. Turning off the TV gives you a chance to be with your family and friends. Going without it frees up valuable time that could be spent reading a good book, writing, drawing, or discovering something else that may interest you.

There are many organizations that support TV-Turnoff Week, including The Boys and Girls Clubs of America, YMCA, Girl Scouts USA, and Big Brothers/Big Sisters of America．Even First Lady Laura Bush is a supporter. "Television is no substitute for a parent. It doesn't help develop language skills; it's simply background noise," says Mrs. Bush.

Even kids who may not have liked going without TV have discovered the benefits. "I really didn't like TV-Turnoff Week except I did notice that my grades went up and I was in a good mood all week," said Drew Henderson, a student in Donora, Pennsylvania.

小题1:The TV-Turnoff Network started TV Turnoff Week to _____.

A．to get people to spend more time doing more productive things

B．to keep kids from participating in healthy physical activities

C．to advise people not to buy television sets

D．to persuade more people to join the organization小题2:Which is not the advantage of turning off the TV?

A．Giving you a chance to be with your family and friends.

B．Sparing more time reading books.

C．Developing language skills.

D．Participating in healthy physical activities.小题3:Laura Bush must be _____.

A．the first woman to support TV-Turnoff Week

B．the wife of American President

C．the first woman to organize TV-Turnoff Week

D．the first lady in the Boys and Girls Clubs of America小题4: Drew Henderson’s words in the last paragraph imply that _____.

A．he doesn’t like TV-Turnoff Week

B．he doesn’t support TV-Turnoff Week at all

C．it’s unnecessary to have TV-Turnoff Week

D．he doesn’t support TV-Turnoff Week until he finds it does good to his study.

国家政治保卫局是我国最早的人民 * * 的公安保卫机关。 ( )

PVC、PICC、CVC、PORT附加的无针接头，应至少每（）更换一次。

A.1天

B.3天

C.5天

D.6天

E.7天

邮政设备出现（）情况时，相应保护必须可靠动作，使包件分拣机停止运行。

A.当牵引超载超过额定量的15%时

B.当牵引超载超过额定量的10%时

C.运行速度低于额定速度的95%时

D.运行速度低于额定速度的85%时

E.张紧限位行程开关动作时