机件的抗疲劳能力与其制造材料有关,而与机件的表面质量无关。
参考答案:对
I am lucky ______ the thing I enjoy doing most is ______ I've ended up doing.
A.when... that
B.if...what
C.that... what
D.that... that
简述发展中国家报业体制的类型。