Question

【题目】It is high time that we(concentration) on protecting the environment.

Answer 1

【答案】concentrated/should concentrate
【解析】句意：到时间我们要关注于保护环境的时间了。It is high time that...属于虚拟语气谓语动词用动词过去时或者should+动词原形。故填concentrated/should concentrate。