A、<span style="font-size:16px;font-family:'Times New Roman','serif'"> <img src="https://s3.cn-north-1.amazonaws.com.cn/qingshuxuetang/ueditor/jsp/upload/image/20160108/1452224157134001743_a.png" title="4974555526409082" alt="a.png"/></span>
B、<img src="https://s3.cn-north-1.amazonaws.com.cn/qingshuxuetang/ueditor/jsp/upload/image/20160108/1452224185394086899_b.png" title="7070308754668635" alt="b.png"/>
C、<img src="https://s3.cn-north-1.amazonaws.com.cn/qingshuxuetang/ueditor/jsp/upload/image/20160108/1452224217280010672_c.png" title="19684341973121711" alt="c.png"/>
D、<img src="https://s3.cn-north-1.amazonaws.com.cn/qingshuxuetang/ueditor/jsp/upload/image/20160108/1452224382938006626_d.png" title="586416981720676" alt="d.png"/>