下列疾病出现气管向健侧移位的是()
A.慢性阻塞性肺气肿
B.严重气胸
C.肺炎球菌肺炎
D.严重肺不张
E.慢性支气管炎
参考答案:B
In that school, English is compulsory for all students, but French and Russia are ____ .
A.special
B.optional
C.regional
D.original
粉尘按理化性质分为.()、()、()。