He be in the dormitory now. I met him in the library just a moment ago.
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We try to speak English whenever and wherever we can; otherwise, we have littlechance to practice our English.
Henry have arrived in Shanghai by now, for the plane took off (起飞) three hours ago.
1、管径为200毫米的铸铁管的表示为DN200
A. 对
B. 错
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