如图所示，在x轴上方存在着垂直于纸面向里、磁感应强度为B的匀强磁场，一个不计重力

中华人民共和国历史上最大一起冤案的受害者是[ ]

A．彭德怀

B．刘 * *

C．林彪

D．邓 * *

阅读理解。

     The dog, called Prince, was a clever animal and a slave to Williams. From morning till night, when Williams

was at home, Prince never left his sight. The dog had a number of duties, for which Williams had patiently

trained him and, like the good pupil he was, Prince lived for the chance to show his abilities.

     When Williams wanted to put on his boots, he would say "Boots" very quietly and within seconds the dog

would drop them at his feet. At nine every morning, Prince ran off to the store, returning shortly not only with

Williams' daily paper but with a packet of cigarettes. A gun dog by breed (品种), Prince had a large soft mouth

for the safe carrying of hunted creatures, so the paper and the cigarettes came to no harm, never even showing

a tooth mark.

     Williams was a railway man, an engine driver, and he wore a uniform which smelled of oil fuel. He had to

work at odd times-"days", "late days" or "nights". Over the years Prince got to know these periods of work and

rest, knew when his master would leave the house and return, and the dog did not waste this knowledge. If

Williams overslept, as he often did, Prince barked at the bedroom door until he woke, much to the anger of the

family. On his return, Williams' slippers were brought to him.

     A curious thing happened to Williams during the snow and ice of last winter. One evening he slipped and

fell on the icy road somewhere between the village and his home. He was so badly injured that he stayed in bed

for three days; and not until he got up and dressed again did he discover that he had lost his wallet containing

over fifty pounds. The house was turned upside down in the search, but the wallet was not found. However,

two days later-that was five days after the fall, Prince dropped the wallet into Williams' hand. Very muddy and

wet through, the little case still contained fifty-three pounds, Williams' driving license and a few other papers.

Where the dog had found it no one could tell, but he had found it and recognized it probably by the slight oil

smell on the worn leather.

1. What does the passage tell us about gun dogs?

A. Their teeth are well-developed when they are very young.

B. They can carry back hunted birds without hurting them.

C. They are fed well, producing many young dogs.

D. They are the most intelligent of all dogs.

2. How did Prince perform his duties?

A. He did his best but was not often successful.

B. He did them unwillingly but got them over.

C. He had few opportunities to do them.

D. He was delighted to show them off.

3. Williams did not realize his loss until several days later because _____.

A. he trusted the dog to find the wallet

B. he had left the wallet on the train

C. he had no chance to feel in his pockets

D. he was busy with his work all the time

4. What might help Prince to find Williams' wallet?

A. The remaining smell of fuel on the case.

B. The photo on Williams' driving license.

C. The footprints of Williams' in the snow.

D. The strong smell of the worn leather.

5. What does the writer think of Prince?

A. Skillful and gentle.

B. Clever and amusing.

C. Proud and fierce.

D. Devoted and smart.

国际条约和国际惯例对于我国国内的国家机关、公职人员和公民及社会组织具有约束力，因此是我国的法律渊源之一。 ( )

自密实混凝土应用技术规程（JGJ/T283-2012）：钢管自密实混凝土结构浇筑时，混凝土最大倾落高度大于（）时，应采用串筒、溜槽、溜管等辅助装置进行浇筑。

A.4米

B.5米

C.7米

D.9米