白塞病消化道基本病变是（）
A.右下腹痛
B.多发性溃疡
C.吞咽困难
D.纳差、腹泻
E.恶心、呕吐
参考答案：B
.
He was feeling bad. He went to work, _______, and tried to fix his attention on it.
A．however
B．so
C．although
D．while
如何实现有效的行政沟通？
