下列属阻塞性吞咽困难的疾病是（）。
A.食管异物
B.纵隔肿瘤
C.软腭瘫痪
D.食管瘢痕狭窄
E.咽部溃疡
参考答案：A, B, D
----Where have you been?
---- I _______ stuck in the traffic. I ________ here earlier.
A．had got; would have been
B．have got; would be
C．got; had done
D．got ; would have been
EPON是基于以太网方式的（）。
A.无源光网络
B.有源光网络
C.光分配网络
D.局域网
