在常用焊接方法中,气焊的加热面积最小,激光焊的最大功率密度最大。( )
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焊条电弧焊的热效率高于埋弧焊。( )
A. 对
B. 错
Read the text Home Entertainment in the USA, and fill in the blanks in no more than three words in each blank.Leisure activities in the USA:Different age groups spend reading, playing video games or using a computer for leisure:4. People aged 75 and over read about ___ per weekend day, play video games and use a computer for about ____.5. People aged 15 to 19 read for an average of only ____ per weekend day, but spend _____ playing video games or using a computer.6. Now more and more older people are ___________ and visiting ____________ like Facebook and MySpace that was something almost only young people did.
SLPC单回路可编程控制器模拟量输出4-20mA的通道是:
A. Y0
B. Y1
C. Y2
D. Y3
关于微分先行的PID算法,下列说法正确的是:
A. 不对给定值进行比例运算
B. 不对给定值进行积分运算
C. 不对给定值进行微分运算
D. 不对给定值进行比例、积分运算