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问题 解答题

一个圆环的外圆的周长是62.8cm，内圆的周长是15.7cm，求这个圆环的宽度．

答案

62.8÷3.14÷2-15.7÷3.14÷2，

=10-2.5，

=7.5（cm）；

答：圆环的宽度7.5厘米．

听力题

I’m Yuan Longping born into a poor farmer’s family in 1931 when farmers in China used to live a hard life．For d        , they struggled to search for ways to increase rich harvests, but without success. Thanks to my research on the hybrid rice that has a high output, which makes_______possible to produce harvests twice as large as before_____   expanding the area of fields, which m       （意味）22% of the world’s people rid themselves of h     (饥饿). I am circulating this knowledge in many countries to increase their harvest. Therefore, I am c       “father of hybrid rice” In addition , I am s        （满意）with my simple life. I c        little for money. In my free time I love listening to music, playing mah-jongg and reading. Look at my s        face and arms and my slim, strong body and you will think I’m __       like a farmer than a scientist.
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问答题

请简述影响预后研究质量的因素。
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