按GB 150-89标准附录H的规定,若为了探测细小的缺陷,可将工件预热到()℃,然后进行渗透
A、30-40
B、40-50
C、50-60
D、>60
参考答案:B
The boy is _______ my sister, so he sits in front of her.
A.as tall as
B.taller than
C.not as tall as
D.the tallest
带式输送机3根上托辊形成一个槽形断面,槽形角一般为()。
A、15°
B、25°
C、30°
D、35°