单项选择题
A.MR=MCB.MR=SMC=LMCC.MR=SMC=LMC=SACD.MR=SMC=LMC=SAC=LAC
A.P=MC B.P=SAC的最低点的值 C.P最高 D.MR=MC
A.P=MR=MCB.P>MR=ACC.P>MR=MCD.P>MC=AC