势成骑虎

if you ride a tiger, it's hard to get off (idiom); fig. impossible to stop halfway

power / influence / potential / momentum / tendency / trend / situation / conditions / outward appearance / sign / gesture / male genitals

surname Cheng

to succeed / to finish / to complete / to accomplish / to become / to turn into / to be all right / OK! / one tenth

(Tw) saddle horse / mounted soldier

to sit astride / to ride (a horse, bike etc) / classifier for saddle horses

tiger / CL:隻|只[zhi1]