分枝杆菌属最主要的特点是（）
A.有分枝生长的趋势
B.细胞壁脂质含量高
C.具有抗酸性
D.无鞭毛、无芽胞
E.生长缓慢
参考答案：B
My friend has returned from the UK. She ______ at Oxford for four years, during which we communicated with each other on the Internet.
A．studied
B．has studied
C．had studied
D．has been studying
下列哪项因素与心悸的形成无关 （）
A.心虚胆怯
B.心血不足
C.心阳虚衰
D.瘀血阻络
E.风热外袭
