下列物质中，在核糖体上合成的是( ) ①肾上腺素 ②突触后膜上的受体 ③淀粉 ④唾液淀粉酶 ⑤纤维素 ⑥胰高血糖素
A. ①③④
B. ②③⑤
C. ②④⑥
D. ①④⑥
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What does the text mainly discuss on Canada
A. The position, population and history of Canada.
B. The position, population and industry of Canada.
C. The position, population and different national races of Canada.
D. The position, history and different national races of Canada.
It has been stated in the passage that the growth of specialist societies and periodicals has helped scholars to ______.
A. spend less time traveling
B. cut down research costs
C. develop their ideas more quickly
D. keep up with current developments
Slavery was ______ in the U.S. in the 19th century.
A. retailed
B. canceled
C. abolished
D. stroked
《天净沙·秋思》是一首( )
A. 套数
B. 散曲
C. 南曲
D. 小令
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