单选题 It is (necessary) that the (customs) (of all) nations (must be respected).
【正确答案】 D
【答案解析】虚拟语气用法错误,应改为(should)be respected。在it is necessary/important that... (做…是必要的/重要的)句型中,要用虚拟语气,其构成是should十动词原形,should可省。