炼油厂常用的垫片有哪些？
参考答案：
橡胶石棉板、金属包石棉垫片、缠绕式垫片、齿型垫、金属垫圈。
If people _____ the importance of living a low-carbon life earlier, there _____ so many environmental
problems now. [ ]
A. realized; wouldn't be
B. had realized; wouldn't be
C. had realized; wouldn't have been
D. realized; wouldn't have been
肾病综合征最根本的病理生理改变是（）
A.水肿
B.大量蛋白尿
C.电解质紊乱
D.低蛋白血症
E.高胆固醇血症
