Last summer I took a course on ______ poisonous gases.

A．what to deal with

B． how to deal with

C．what to be dealt with

D． how to be dealt with

肺癌钙化形成的病理基础是（）

A.肿瘤瘢痕收缩

B.瘤内含气、扩张的细支气管

C.肿瘤内残存正常含气肺组织

D.肿瘤钙化或包埋原有钙化灶所致

E.癌细胞浸润及间质反应