据新华社报道,2010年我国粮食产量将达到540 000 000 000千克,用科学记数法可表示为______千克.
540 000 000 000=5.4×1011千克.
In painting a lifeboat following its overhaul,which parts must be painted bright red?()
A.the top 2-1/2 inches of each side
B.the releasing gear lever
C.the fuel tanks
D.the thwarts
操作气焊或气割时,氧气瓶或乙炔瓶的水平距离不得小于(),并应远离火源()以上。