catch on

理解，明白

cataleptic, catalog, catalogue, catalogue (US also catalog), catalysis, catalyst, catalytic, catalyze, catamaran, catapult, cataract, catarrh, catastrophe, catastrophic, catastrophically, catcall, catch, catch at, catch crop, catch fire, catch one's breath, catch one's eye, catch sb.'s eye, catch sight of, catch the eye, catch up, catch up on, catch up with, catch-all, catcher, catching, catchment area, catchpenny, catchphrase, catchword, catchy, catechism, catechize, catechise, categorical, categorically,