when problems crop up惹事;出现变故
crop up on在
begin to crop up露出苗头
problems may crop up突然出现的问题
to crop up蹦出来
crop up here and there层出不穷
to begin to crop up冒头
That crop up for air为了空气拔地而起;为了氛围拔地而起
new problems crop up unexpectedly节外生枝
PHRASAL VERB（动词词组） If something crops up, it appears or happens, usually unexpectedly. 意外出现; 突然发生
His name has cropped up at every selection meeting this season.
他的名字出人意料地出现在了本季的每次选拔会上。