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问题 单项选择题

胎儿脊柱的正常声像图表现为：①纵切面呈一条排列整齐的光带；②纵切面呈串珠状的小光团排列成两条弓状平行光带；③纵切面呈一连串念珠状的小光团；④横切面可见3个强回声团，呈"品"形（）

A.①②③

B.①③

C.②④

D.④

E.①②③④

答案

参考答案：C

单项选择题 A型题

超声波是怎样产生的（）。

A.换能器的逆压电效应

B.换能器的正压电效应

C.换能器向人体发送电信号

D.换能器的热效应

E.换能器的机械效应
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填空题

Nature is one of the main sources of inspiration(灵感来源) for artists. We’ve seen many works of art that are about trees, but in South Africa, there is a special work of art that can amaze you --- a bar in a tree.

The bar, named Sunland Big Baobab,    小题1:  a hollow tree. The huge tree is the wildest baobab tree(猴面包树---非洲) on record, which is a type of tree normally found in hot,   小题2:

Africa. The large tree, twenty two metres in    小题3: and forty-seven metres in girth(周长), stands on Sunland Farm. More amazingly, the tree is    小题4:  the oldest tree in the world --- it is about 6,000 years old!
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