汽油的辛烷值代表汽油的（），辛烷值高，其（）好。
参考答案：抗爆性、抗爆性
上消化道出血特征性的表现为
A．失血性贫血
B．呕血与黑便
C．肠性氮质血症
D．失血性周围循环衰竭
E．网织红细胞持续升高
同义句改写。
1. The film began 20 minutes ago.
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2. I think Lian yungang is more beautiful than any other city in Jiangsu.
3. My home is half an hour's walk from school.
