低密度介质可以通过调整（）调整其密度。
A．固相含量
B．处理剂浓度
C．空气含量
参考答案：C
My father was so tired that he fell asleep he went to bed. [ ]
A. as if
B. even though
C. ever since
D. as soon as
以下不符合Crohn病的是（）
A.多发生于回肠末端及近端结肠
B.糊样便无脓血
C.病变呈连续性
D.易有瘘管形成
E.一般累及肠壁全层
