crop upvi phrasalphrasal verb, intransitive: Verb with adverb(s) or preposition(s), having special meaning and not taking direct object--for example, "make up" [=reconcile]: "After they fought, they made up."
informal (appear suddenly)
发生，显现
被提到 bèi tí dào
备注: often used in the continuous after "keep", "start"
Problems started cropping up when we installed the new software.