2, Dynamical dark energy*o Quintessence: L=(80)-Vo 1/202-T 1≤w≤1 1/2p-+1 ≈"()≤H0~10-3 ek Flat po otential Phantom: L=-(8P)2-v( w<-1 K-essence: L=L(a, 08, ) w<-1,w> Cannot cross -1 no-go theorem Feng, Wang Zhang, PLB(2005); Vikman, PRD(2005); Zhao, Xia, Li, Feng Zhang, PRD(2005); Xia, Cai, Qiu, Zhao &Zhang, IJMPD (2008) Quintom: w crosses-1 L=(ao)-(ap)-voe) feng, Wang& Zhang PLb(2005) C L=(p)+,n2(Oy)2-V() i, Feng Zhang, JCAP (2005) M L=-v(D)1-a2do9+Bo2o Cai, i, Lu, Piao, Qiu&Zhang, PLB(2007)2, Dynamical dark energy 1 2 ( ) ( ) 2 L V =  −   2 2 1/ 2 1/ 2 V w V   − = + Quintessence: −   1 1 w w 0 Phantom: 1 2 ( ) ( ) 2 L V = −  −   w −1 meff V H eV 33 ''( ) 0 ~10−    K-essence: L L( , )  =       w w  −  − 1, 1 Cannot cross -1, no-go theorem Feng, Wang & Zhang, PLB(2005);Vikman, PRD(2005);Zhao, Xia, Li, Feng & Zhang, PRD(2005); Xia, Cai, Qiu, Zhao &Zhang, IJMPD(2008) Quintom: 2 2 1 2 1 2 1 1 ( ) ( ) ( , ) 2 2 L V =  −  −     Feng, Wang & Zhang, PLB(2005) 2 2 2 2 1 ( ) ( ) ( ) 2 c L V M =  +  −    Li, Feng & Zhang, JCAP(2005) w crosses -1 ……… Flat potential 2 2 2 2 1 ( ) ( ) ( ) 2 c L V M =  +  −            2 L = −V( ) 1− '  + ' Cai,Li,Lu,Piao,Qiu&Zhang, PLB(2007)