Definition: to happen, often without being planned Level: B2
在东行车道发生了一起涉及超过十辆车的事故。
An accident involving over ten vehicles has ___occurred in the east-bound lane.
如果在服药期间出现任何这些症状，请立即咨询医生。
If any of these symptoms ___occur while you are taking the medicine, consult your doctor immediately.
