胰腺癌常见的首发症状是
A．腹泻B．消瘦C．黄疽D．腹痛E．纳差
参考答案：D
There are many people downstairs. What do you think ______?
A．to happen
B．happening
C．is happened
D．has happened
采用液压或气动机构时，其工作压力大于1MPa（表压）时，应有压力安全释放装置（）
