天然气水合物的形成和哪项没有关系()。
A.压力
B.温度
C.气体流速
D.气体组分
参考答案:C
肺痈的诊断,主要应掌握下列哪项()
A.咳嗽
B.胸痛
C.发热口干
D.咳吐腥臭脓痰
E.脉滑数
They have been skating _______. [ ]
A. for three hours ago
B. since three hours ago
C. three hours ago
D. since three hours