【单选题】Criticism and self-criticism is necessary _____ it helps us to correct our mistakes.
【单选题】“海带炖排骨”和“紫菜蛋汤”是人们喜爱的佳肴.你知道海带和紫菜与下列哪种植物同属于一类( )
【简答题】下面哪个是正方形? [ ] 哪个是长方形? [ ] A. B. C. D.
【判断题】50%存在于人体骨骼和牙齿中的微量元素是钙。
【单选题】Criticism and self-criticism are necessary __________they may help us to find out and correct our mistakes.