粘性土抗剪强度库仑定律的总应力的表达式()，有效应力的表达()式()。
参考答案：
τf=c+σtanφ,τf=c1+σ1tanφ1
After Billy said he would ride a bicycle safely, his father _____ to him and bought him one.
A．gave away
B．gave in
C．gave up
D．gave out
疑“胆总管结石”，应首选（）
A.口服胆囊造影
B.ERCP
C.低张十二指肠造影
D.肠系膜上动脉造影
E.腹部平片
