情态动词should的用法 — 英语填空题
题目
完成句子（每空一词）：在环保主题班会上，老师总结道："Everyone ___ (should / shouldn't) turn off the lights when leaving the classroom, but students ___ (should / shouldn't) leave rubbish on the playground. If we all follow these rules, our school ___ (should / shouldn't) become cleaner and greener."