Home/backcrossbackcross/bak-kraws, -kros/US // ˈbækˌkrɔs, -ˌkrɒs //UK // (ˈbækˌkrɒs) //溯源,溯溪,溯源活动,溯及既往Definitionsv.有主动词 verb1: to cross with either of its parents.n.名词 noun1: an instance of such crossing. Level 5Browse all words →