甲型肝炎主要传播途径是( )
A．输血
B．性交
C．蚊虫叮咬
D．母婴传播
E．粪一口途径
参考答案：E
The secretary________letters all the afternoon and there are still two letters to finish.[ ]
A. is typing
B. had type
C. has been typed
D. has been typing
定量预测法的优缺点是什么
