出现发绀的高铁血红蛋白血症,血液中高铁血红蛋白含量的临界值为
A.痰有恶臭气味B.黄桃样乳状痰C.黄绿色痰D.痰色白粘稠、牵拉成丝E.微黄奶酪样痰
参考答案:C
Smoking is one of the________causes of cancer, killing millions of people each year. [ ]
A. major
B. similar
C. commercial
D. chemical
简述西方关于国家起源的几种学说。