【单选题】
图示结构截面K剪力影响线是图()。<img src=https://huaweicloudobs.ahjxjy.cn/D8503B836ED96E2CB31C29CE3D1996D3.png title=QQ截图20180421130038.png alt=QQ截图20180421130038.png/>
①
<img src=https://huaweicloudobs.ahjxjy.cn/3908303A9ED6D01EF01111DDFD96F680.png title=1.png alt=1.png/>
②
<img src=https://huaweicloudobs.ahjxjy.cn/E33F2ABB551915541C881B67BFBE367F.png title=2.png alt=2.png/>
③
<img src=https://huaweicloudobs.ahjxjy.cn/A51F1733735267A707DE149490A3DE1D.png title=3.png alt=3.png/>
④
<img src=https://huaweicloudobs.ahjxjy.cn/D1259EC9B0DE8F1EA9A7B4371C54BA81.png title=4.png alt=4.png/>