近年来的研究指出,肽也有构象,如脑啡肽是一个五肽,它有______构象,但肽的构象易变,稳定性远不如蛋白质。
参考答案:β-转角
Two building workers got seriously wounded when the stadium _______.
A.was built
B.was being built
C.built
D.is being built
办理收汇核销的主管机关是国家税务局。