十二指肠球部以下出血
A．腹痛、发热、黄疸B．水量便鲜血C．出血伴腹痛高热D．出血速度慢、便血为主E．出血速度快、呕血或便血
参考答案：C
There was a time_____we went to the country and stayed with the farmers there.
A．which
B．that
C．when
D．while
比较固定汇率制度与浮动汇率制度的优缺点。
