导致X线衰减的原因是()
A.物质和距离
B.X线不可见
C.X线波长短
D.X线能量大
E.X线是电磁波
参考答案:A
The result of the survey shows successful people have in common is they all have confidence.
A.whether; that
B.what; that
C.what; why
D.which; that
废钢的检验项目有斗重、()、()、单重、()。