比针叶材纤维素含量高的造纸植物纤维原料有:()()。
参考答案:麻类;棉纤维
Huangshan is ______ most beautiful tourist site and I want to visit it ______ second time next month.[ ]
A. the; the
B. the; a
C. a; a
D. a; the
油浆系统为什么会结焦?