植物缺乏氮、磷、钾、镁等元素,缺素症状在下部老叶上最先表现出来.
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导热性的大小通常用热导率来衡量,热导率越高的材料其导电性越好。
A. 正确
B. 错误
从微观角度来看,企业年金是市场经济体制下劳动者薪酬福利结构的一部分,工作时间越长,积累资金越多,对员工越有利。
A. 正确
B. 错误
At the same time,it is()for you to signify your acknowledgement of the responsibility for the collision by signing the copies of this letter hereto attached and to return me two copies in due time.
A. essential
B. important
C. good
D. a better operatio