当无设计要求时混凝土梁的保护层厚度不应小于（）。A.20mm B.25mm C.15

男性，31岁，阵发性腹痛4天伴肠鸣、恶心、未吐，12小时来未排便或排气，3年前曾因节段性肠炎行回肠末端切除术，术后一年出现多次腹痛发作，情况与本次相似，查体：腹胀，可见肠型及蠕动波，肠鸣音活既，可闻及气过水声。

本病例最有可能的疾病是（）

A.节段性肠炎

B.结肠癌

C.急性胃肠炎

D.粘连性肠梗阻

E.缺血性肠炎

属于卵巢上皮性肿瘤的是

A．黏液性囊腺瘤
B．无性细胞瘤
C．内胚窦瘤
D．颗粒细胞瘤
E．畸胎瘤

阅读理解

     It seems hard to watch someone yawn and not to yawn ourselves. Even reading about yawning can

make you do it. Now, a new study has found why yawning has such a powerful force.

     Yawning when others yawn, the study suggests, is a sign of pity and a form of social connection. Kids

don't develop this deeply rooted behavior until around age four, the study has found. Kids with autism

(自闭症)are half as likely to catch yawns. In the most serious cases, they never do. Yawning might help

doctors to see whether the children are developing rightly. The work could also lead to a better

understanding of the ways that people communicate and connect.

     "Emotional infection seems to be a born thing that connects us together, "said Molly Helt, a graduate

student in psychology at the University of Connecticut. "Yawning may be part of that. "Inspiration for her

study came when she tried to get her own autistic son to clear his ears on an airplane. She repeatedly

yawned at him, hoping he would yawn back. He never did.

     "The fact that autistic kids don't do it might mean they're really missing out on that emotional

connection with people around them, "she said. "The biggest thing people try to figure out after birth is

how we become humans and understand that humans have minds that are different from others'," she

added. "Autistic people never seem to understand that. "

     Like infectious laughter and crying, scientists have found that yawning is a shared experience that

promotes social connection. Helt said it could fight stress after a period of being nervous and spread a

feeling of calm in a group.

1. What does the new study suggest, according to the first two paragraphs?

A. It is impossible to stop yawning when you see others yawn.

B. Yawning has some mysterious force which is related to God.

C. Children follow others in yawning just after they are born.

D. Yawning is a form of communication.

2. According to Molly Helt, ________.

A. emotions are infectious, but yawning is not

B. yawning helps clear ears on planes

C. humans differ from animals because they communicate with others

D. yawning is a kind of emotional connection among humans

3. Which of the following is NOT true about yawning?

A. It is natural to yawn back if people around you yawn.

B. Some kids are too young to yawn after others.

C. Yawning can be used to test children's development.

D. Kids with autism yawn easily when others yawn.

4. According to the author, infectious yawning________.

A. has a positive effect on social relationships

B. is helpful in curing people of autism

C. helps people develop their brain

D. is most useful in group work

5. The author implies in the last paragraph that________.

A. it is bad manners to yawn on some social occasions

B. yawning can make people feel relaxed

C. yawning is different from infectious laughter and crying in theory

D. the more you yawn, the more you will become nervous and stressful

“西林教案”是清朝地方官员和各族人民反对外国传教士侵略活动的斗争，同时，这一事件也成为法国勾结英国联合对我国发动（）的借口。

A.第一次鸦片战争

B.第二次鸦片战争

C.甲午战争

D.抗日战争

______网络拓扑结构使用一条电缆作为主干电缆，网上设备用从主干电缆上引出的电缆加以连接。

A．星型

B．总线型

C．环型

D．树型