若已确定为胆总管下端梗阻，为明确肿块来源应首选
A．ERCP
B．十二指肠低张造影
C．ECT
D．DSA
E．MRI
参考答案：A
They are against the plan. For it ____ too much farmland.
A．puts up
B．takes up
C．gives up
D．makes up
焊接结构满足哪些基本要求？
