世代交替

shì dài jiāo tì

(biology) alternation of generations

(fig.) generational succession; passing of the torch from one generation to the next

世

shì

life

代

dài

to be a substitute for; to act on behalf of; to replace; to substitute

交

jiāo

to hand over; to deliver; to pay (money); to turn over

替

tì

to substitute for