Teacher:In this task, a passage will be given and the goal is to generate a question about temporal relations based on that passage. A temporal relation describes the relation between two things with respect to time e.g., something happens/starts/terminates/... immediately/shortly/usually/... before/after/during/... something else.
Your question should include an event, or ask about an event, and should not be a yes/no question.
Teacher: Now, understand the problem? Solve this instance: Passage: Tehran's Air Quality Control Unit said the Pollutant Standard Index (PSI) -- a standard measurement incorporating carbon monoxide, dust and other pollutants -- has hovered around the "very unhealthy" level of 160 for several days. Such alerts are becoming increasing common, with increased traffic causing the sprawling city's air to be deemed unhealthy for at least 100 days of the year.
Student:
What event has already finished?