单选题如图所示，等截面梁的1/3跨度处挠度为（　　）。<br/> <br/> <img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/8325548_0.jpg"><br/> <img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/8325548_0_1.png">