β地中海贫血与下列何项无关（）
A.控制基因突变
B.肽链结构异常
C.肽链合成速度减慢
D.肽链数量不平衡
E.临床表现为贫血、脾大、黄疸
参考答案：B
This year they have produced_________ they produced the year before last.
A．twice many cars as
B．twice as many cars as
C．twice more than cars
D．twice the cars of
奶的主要卫生问题是
A．微生物污染B．加入不洁净水C．发酵D．脂肪含量不够E．容器不卫生
