无效造血过多与何项无关( )
A．分裂周期延长B．红细胞本身缺陷C．幼红细胞成熟障碍D．维生素B12供量过多E．以上都是
参考答案：D
正常肠鸣音是
A．1次/3～5分B．2～4次/分C．4～5次/分D．3～6次/分E．6～10次/分
To study a foreign language,（）
A.a good dictionary should be bought
B.buying a good dictionary is necessary
C.you should buy a good dictionary
D.it is necessary that you will buy a good dictionary
