下列关于蛋白质的论述,正确的是[ ]
A.每种蛋白质都含有C、H、O、N、S等元素
B.每种蛋白质的分子结构中都有肽键
C.蛋白质是调节新陈代谢的唯一物质
D.酶都是蛋白质
答案:B
For some time, Chinese people, under the leadership of CPC, ________ the contents of the Scientific Development Concept in the course of practicing socialism in China.
A.had been improving
B.have been improving
C.were improving
D.improved
热液成矿作用的类型?