对容易引起冻害果蔬采取保温措施;对易高温腐烂的果蔬,在运输前进预冷。
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当焊条的包装破损或受潮较严重时,才需要烘烤,但烘烤温度不应超过()。
A. 100℃
B. 50℃
当液压缸活塞所受的外力一定时,活塞的截面积越大,其所受的压力就()。
On a hydrocarbon flammability chart the line which extends from 0% to 21.8% oxygen,lying tangent to the flammability range,is called the().
A. mimimum oxygen content line
B. critical displacement line
C. critical dilution line
D. upper threshold limit