甲型病毒性肝炎的典型临床表现为（）
A.食欲不振，厌油腻
B.恶心、呕吐
C.发热
D.全身乏力
E.出现黄疸尿色加深
参考答案：A, B, C, D, E
When you play football, it's dangerous to _______ players and falling down. [ ]
A. knock into
B. knock at
C. knock on
D. knock off
试述矿物的概念及其肉眼鉴定的主要依据。
