弯曲杆件的画线要掌握:一是构件的外形控制线、间隔线,二是合角缝隙线,三是中位分隔制作控制线;这三种不同的线是弯曲杆件画线的基础。
参考答案:错
某2.0L硫酸溶液中含有1.0mol H2SO4.试计算:
(1)溶液中H2SO4的物质的量浓度;
(2)向上述溶液中加入足量的铁粉,产生气体的体积(标准状况);
(3)假设反应前后溶液体积不变,则所得溶液中Fe2+的物质的量浓度.
Which of the following is true about China
A.The oil demand growth in the second quarter is 12.3%.
B.Restrictions on trucking and economic growth will help reduce the oil demand.
C.Extra refining capacity is also under tight control.
D.The oil demand in the third quarter will fall by 9%.