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【简答题】
分馏就是按照组分( )的差别将石油 “ 切割 ” 成若干 “ 馏分 ” 。
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反馈参考答案：
举一反三
【单选题】关于原核生物的RNA合成,下列哪种说法是错的?
A.
合成的RNA链与模板链是反向平行的
B.
RNA链合成的准确起始需要ρ因子
C.
RNA链合成时,第一个核苷酸常为嘌吟核苷酸
D.
RNA链合成时,DNA结构暂时发生变化
【单选题】Great changes _____ in our country since twenty years ago. [ ]
A.
have taken place
B.
have been taken place
C.
took place
【单选题】Great changes _____ in my hometown since 1980. [ ]
A.
have been taken place
B.
took place
C.
have taken place
D.
were taken place
【单选题】—How do you like China? —Great changes _______ since I _______ here 8 years ago.
A.
have taken place; came
B.
took place; have come
C.
took place; came
【单选题】Great changes ______ in China since1978.
A.
have been taken place
B.
had taken place
C.
have taken place
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