提出建议的句型 — 英语选择题
题目
Lily 发现教室里很多人离开时忘记关灯，她想向同学们提出建议。下列句子中表达建议正确且最得体的一项是：A. You had better to turn off the lights before leaving. B. You'd better turn off the lights before leaving. C. You'd better turning off the lights before leaving. D. You had better not turning off the lights before leaving.