问题
单项选择题
DNA拓扑异构酶的作用是
A．去除引物，填补空缺
B．使双螺旋DNA链缺口的两个末端连接
C．解除DNA旋转引起的打结、缠绕
D．将双螺旋解链，便于复制
答案
参考答案：C
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DNA拓扑异构酶的作用是
A．去除引物，填补空缺
B．使双螺旋DNA链缺口的两个末端连接
C．解除DNA旋转引起的打结、缠绕
D．将双螺旋解链，便于复制
参考答案：C
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| Elena Desserich was a little girl. She loved to 1 and write. Elena dreamed of becoming an artist when she grew up-but sadly, she 2 had the chance to be an adult. When elena was 5 years old, the 3 said that she had brain cancer (癌症) and only had 135 days to 4 . Elena 5 the long days in hospital working on her painting, which were full of hearts and smiling families. 6 of her painting was shown in a gallery (画廊), right next to a Picasso's painting. Soon she lost the use of her 7 , and she began to "talk" with her family by writing notes. When Elena died, her parents were very sad, 8 they knew the day would come. When they were tidying up her things, they began to find notes. All through her final days, Elena was writing love notes to her family and hiding (藏) 9 in secret places in the house. Her parents started to collect them and all the 10 would say "I love you Mum, Dad and Grace." They kept finding them-the amazing gift from Elena. | ||||
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