主要分布于中纵隔的肿瘤有()
A.畸胎瘤
B.霍奇金病
C.心包囊肿
D.神经源性肿瘤
E.支气管囊肿
参考答案:B, C, E
I had just stepped out of the bathroom and was busily drying myself with a towel ______ I heard the steps.
A.while
B.when
C.since
D.after
单位时间内,沿热流方向,导热体两侧温差为1℃时,通过单位长度所传导的热量称为().
A.总传导系数
B.导热系数
C.反射率
D.吸收率