下列命题中正确的是<br/> A、每个初等矩阵都是可逆的.<br/> B、初等矩阵的转置也是初等矩阵. <br/> C、如果 <img src="https://static.zxtiku.com/wangke/imgs/topic/44660d649db7720cc670d18af68834de.jpg"/> 矩阵 <img src="https://static.zxtiku.com/wangke/imgs/topic/8124fa7a2daf7d288ce5e68f3e57a158.jpg"/> 的秩 <img src="https://static.zxtiku.com/wangke/imgs/topic/b65f16840806d104f7849c676e79f163.jpg"/>, 则 <img src="https://static.zxtiku.com/wangke/imgs/topic/8135ba7d69382999b57e5f5d68e6a55c.jpg"/> 的(相抵)等价标准形为 <img src="https://static.zxtiku.com/wangke/imgs/topic/44aa095cdca70541c6eb2600c2565686.jpg"/><br/> D、如果 <img src="https://static.zxtiku.com/wangke/imgs/topic/49ba25e8c9c8a6d5bb06d69ed1511d93.jpg"/> 矩阵 <img src="https://static.zxtiku.com/wangke/imgs/topic/8124fa7a2daf7d288ce5e68f3e57a158.jpg"/> 的秩 <img src="https://static.zxtiku.com/wangke/imgs/topic/d76431ac82ce742ff2f999a89fac28ab.jpg"/> 则 <img src="https://static.zxtiku.com/wangke/imgs/topic/8124fa7a2daf7d288ce5e68f3e57a158.jpg"/> 的(相抵)等价标准形为 <img src="https://static.zxtiku.com/wangke/imgs/topic/3f77ef441b184efdb3cba6d78e551613.jpg"/><br/> E、如果 <img src="https://static.zxtiku.com/wangke/imgs/topic/087a85c2f2ca8bfec3649e83d743bf3b.jpg"/> 阶矩阵 <img src="https://static.zxtiku.com/wangke/imgs/topic/8124fa7a2daf7d288ce5e68f3e57a158.jpg"/> 通过初等行变换化成的某个阶梯形矩阵有 <img src="https://static.zxtiku.com/wangke/imgs/topic/47d06919fa3f658afefca6a00cb6255d.jpg"/> 个阶梯头, 则 <img src="https://static.zxtiku.com/wangke/imgs/topic/8124fa7a2daf7d288ce5e68f3e57a158.jpg"/> 必可逆.