心内膜垫缺损的心电图一般可有如下改变
A．电轴左偏
B．电轴右偏
C．P-R间期缩短
D．P-R间期延长
E．I度A-V阻滞
参考答案：A,D,E
在下列免疫细胞中能进一步分裂和分化的是[ ]
A．效应T细胞
B．浆细胞
C．记忆细胞
D．吞噬细胞
Don't do any other things while you are doing your homework. So please _____ your MP3. [ ]
A. turn up
B. turn down
C. turn on
D. turn off
