【单选题】Only then _____ how much damage had been caused. [ ]
【单选题】关于胶原的描述错误的是哪一项? ______ 。
A.
是动物体细胞外基质中一个高度特化的纤维蛋白家族
【单选题】为了保证棘轮在工作中的( )可靠和防止棘轮的( ),棘轮机构应当装有止回棘爪。
【单选题】She was () because she had been put into a dorm that had people from a variety of ethnic backgrounds.