判定下列何项正确()A．MRI图像呈黑色时，称为低强度信号，也即长T1加权像，或短T

男性，45岁，反复出现胸骨后烧灼样痛，多在餐后出现。

其最可能的诊断是（）

A.食管癌

B.纵隔肿瘤

C.变异型心绞痛

D.反流性食管炎

E.陈旧性心肌梗死

The policemen ______ coming.             [ ]

A. is                

B. are         

C. has         

D. have

"It’s no use, Mum," said Johnny. "I’m just no good at dancing."

"You’ve got to keep trying. Tonight will be (1) , dear. Try a turn with that pretty Lisette. "

Johnny (2) . Every Saturday night used to be the best of the week. He and his parents went to the (3) at the Club, where his hero, Alcide, played the accordion with the band. But lately everything had changed. Now that Johnny was older, he was (4) to dance with a girl!

(5) Johnny and his parents arrived at the Club, music had already started. Johnny got up his (6) to approach Lisette. "May I have this dance" Johnny asked. "That’s all right."said Lisette. Johnny struggled to keep up with Lisette’s (7) steps, but he was always one beat behind her. Then Johnny heard his friend Pierre say, "Look! Johnny has two left feet!" (8) burst from the crowd. Johnny (9) and ran outside, determined never to go to another dance.

The next Saturday, Alcide (10) to Johnny’s house for some potatoes. He happened to hear Johnny playing the accordion. Alcide’s eyes (11) . "Bring that accordion and play some songs tonight," Alcide said. Then he drove off, leaving Johnny staring open mouthed (12) him.

At the Club, Johnny scanned the crowd for Lisette and (13) her. The band played for a long time before Alcide said, "Dear friends, I got a (14) for you tonight. Young Johnny is going to join us!" (15) , Johnny stepped up on the platform, his eyes on the floor. He began to play, and the band (16) behind him. When the song ended, he heard cheers. Johnny kept playing until the dance was (17) . "You did a fine job tonight. Play with us again next Saturday night, " Alcide said. "Yes, sir! " said Johnny. (18) he went outside, Johnny saw Lisette and her friends near the door. Lisette stepped (19) , smiling. "You played really good tonight!" she said."Thank you," Johnny blushed. As he walked on, Pierre (20) moved out of the way for him to pass.Johnny patted his accordion. Come to think of it, in his whole life, he had never once seen Alcide out on the dance floor.

11().

A．opened

B．rolled

C．sharpened

D．widened

某钨矿企业(一般纳税人)2008年5月份生产开采钨矿800万吨，直接对外销售300万吨，每吨不含税售价46元。以部分钨矿原矿入选精矿 80万吨，选矿比为30%，当月购进生产材料取得专用发票注明税金124万元。当地钨矿石适用税额每吨3元。该企业当月份应纳的资源税税额和增值税合计为( )。

A．1700万元

B．2240万元

C．3922万元

D．3947万元

Whether to teach young children a second language is disputed among teachers, researchers and pushy parents. On the one hand, acquiring a new tongue is said to be far easier when young. On the other, teachers complain that children whose parents speak a language at home that is different from the one used in the classroom sometimes struggle in their lessons and are slower to reach linguistic milestones. Would a 15-month-old child, they wonder, not be better off going to music classes

A study just published in the Proceedings of the National Academy of Sciences may help resolve this question by getting to the point of what is going on in a bilingual child’s brain, how a second language affects the way he thinks, and thus in what circumstances being bilingual may be helpful. Agnes Kovacs and Jacques Mehler at the International School for Advanced Studies in Trieste say that some aspects of the cognitive development of infants raised in a bilingual household must be undergoing acceleration in order to manage which of the two languages they are dealing with.

The aspect of cognition in question is part of what is termed the brain’s “executive function”. This allows people to organise, plan, prioritise activity, shift their attention from one thing to another and suppress habitual responses. Bilingualism is common in Trieste which, though Italian, is almost surrounded by Slovenia. So Dr. Kovacs and Dr. Mehler looked at 40 “preverbal” seven-month-olds, half raised in monolingual and half in bilingual households, and compared their performances in a task that needs control of executive function.

First, the babies were trained to expect the appearance of a puppet on a screen after they had heard a set of meaningless words invented by the researchers. Then the words, and the location of the puppet, were changed. When this was done, the babies who speak only one language had difficulty overcoming their learnt response, even when the researchers gave them further clues that a switch had taken place. The bilingual babies, however, found it far easier to switch their attention — counteracting the previously learnt, but no longer useful response.

Monitoring languages and .keeping them separate is part of the brain’s executive function, so these findings suggest that even before a child can speak, a bilingual environment may speed up that function’s development. Before rushing your offspring into bilingual kindergartens, though, there are a few cautions. For one thing, these extraordinary cognitive benefits have been demonstrated so far only in “crib” bilinguals — those living in households where two languages are spoken routinely. The researchers speculate that it might be the fact of having to learn two languages in the same setting that requires greater use of executive function. So whether those benefits apply to children who learn one language at home, and one at school, remains unclear.

How does a second language affect the way a young child behaves according to the new study（）

A. It shortens his focus time on anything learnt

B. It always switches his attention to new information

C. It makes him able to predict the appearance of a person

D. It makes him far easier to overcome his learnt response