可以促进结肠运动的是（）
A.5-羟色胺
B.去甲肾上腺素
C.血管活性肠肽
D.胰泌素
E.生长抑素
参考答案：A
He had been ill for a long time and _________ he was left behind in his work。
A．however
B．consequently
C．otherwise
D．but
试述直肠肛管周围间隙。
