医学化学 PC-C C Br>H,Cl>F Z-1-氟-1-氯-2-溴乙烯 Z-2-bromo-1-chloro-1-fluoroethene 医学化学 C C F Cl H Br Br>H，Cl>F Z-1-氟-1-氯-2-溴乙烯 Z- 2-bromo -1-chloro- 1-fluoroethene