简述生产S7*0.25*0.18内螺纹管时,如何选择合适的预定径和旋模比?
参考答案:
生产瘦齿时应当尽量减少铜管与螺纹芯头的间距,加大旋模量,以减少变形过程中产生的残齿。
The archaeologists found gold coins and pottery in the lowest level of the site____ they reached three months ago.
A.what
B.for which
C.that
D.to which
发动机点火系火花塞得到的电压约为多少伏:()
A.5000V
B.8000V
C.1200V
D.1500~2000V