【单选题】
<img src=https://huaweicloudobs.ahjxjy.cn/C882D4E24CE7A422C43E328CEEE80176.png title=3.png alt=3.png/>
①
<img src=https://huaweicloudobs.ahjxjy.cn/2723068AD13145C9A4A03B1FB7EE8A18.png title=3-1.png alt=3-1.png/>
②
<img src=https://huaweicloudobs.ahjxjy.cn/DF48FD7C9D373FC3A2EEE7D2A6F3499B.png title=3-2.png alt=3-2.png/>
③
<img src=https://huaweicloudobs.ahjxjy.cn/8875F7E8EB5FC128F956C98FB3D021CA.png title=3-3.png alt=3-3.png/>
④
<img src=https://huaweicloudobs.ahjxjy.cn/101B8268627B9F675FEA4D9CD610C838.png title=3-4.png alt=3-4.png/>
【单选题】
<img src=http://60.205.157.60/course/a@F87801D9001E1076D65A77D630877600.jpg title=单选题图5.jpg alt=单选题图5.jpg/>正方形结构如图5所示，已知各杆的EA都相同，则斜杆1-3的伸长为( )。
①
Δl=2Fa／EA
②
Δl=0
③
Δl= Fa／2EA
④
ABC均错
【多选题】
<img src=https://huaweicloudobs.ahjxjy.cn/EED3B837B4764C1CCF0E2C6CE7F70904.png title=17.png alt=17.png/><img src=https://huaweicloudobs.ahjxjy.cn/24E0907ED0230C3FE1B001D96DCA0640.png title=3.png alt=3.png/>
①
<img src=https://huaweicloudobs.ahjxjy.cn/40D7EEA00B7328C356EA48E7A3FAB0DA.png title=21.png alt=21.png/>
②
<img src=https://huaweicloudobs.ahjxjy.cn/CC7C91517A87C3B43D3CE3AEC8F9933E.png title=18.png alt=18.png/>
③
<img src=https://huaweicloudobs.ahjxjy.cn/47E28456705DD008C90AB7B271A1CD99.png title=20.png alt=20.png/>
④
<img src=https://huaweicloudobs.ahjxjy.cn/04BE897DBF46143673826DF9BAC51021.png title=19.png alt=19.png/>
【单选题】
<img src=https://huaweicloudobs.ahjxjy.cn/D6285B71D99C6E80E73597CB42112FB2.png title=3.png alt=3.png/>
①
<img src=https://huaweicloudobs.ahjxjy.cn/0033BCB2CF606B89AF3D9C47C35F5525.png title=3-1.png alt=3-1.png/>
②
<img src=https://huaweicloudobs.ahjxjy.cn/AA5561F2C1B2F075D208CEA0B318B114.png title=3-2.png alt=3-2.png/>
③
<img src=https://huaweicloudobs.ahjxjy.cn/83E590E39D5DBE3BF3A8F74BEBADD5EB.png title=3-3.png alt=3-3.png/>
④
<img src=https://huaweicloudobs.ahjxjy.cn/DCE52CE9640DAC4EBE4F21C8F90C87F8.png title=3-4.png alt=3-4.png/>
【判断题】
<img src=https://huaweicloudobs.ahjxjy.cn/8C0E234B4BA863BF3E10791840D87CE1.png title=3.png alt=3.png/>
①
正确
②
错误
【单选题】
<img src=https://huaweicloudobs.ahjxjy.cn/EC250FB89851C0D645FB3E99B628EEA0.png title=3.png alt=3.png/>
①
<img src=https://huaweicloudobs.ahjxjy.cn/5610491B4A9BE1855383D5D72F5DF3D8.png title=3-1.png alt=3-1.png/>
②
<img src=https://huaweicloudobs.ahjxjy.cn/84593AFA6F62E31D04EE311CEBF903BF.png title=3-2.png alt=3-2.png/>
③
<img src=https://huaweicloudobs.ahjxjy.cn/6DC4CCE58527DF6BB0F185FC12A67198.png title=3-3.png alt=3-3.png/>
④
<img src=https://huaweicloudobs.ahjxjy.cn/10AFB066C2A0316265C2D56272B0A957.png title=3-4.png alt=3-4.png/>
【单选题】
<img src=https://huaweicloudobs.ahjxjy.cn/E8A3B6E0BABD79C0A4B1085F13E8AECA.png title=3.png alt=3.png/>
①
<img src=https://huaweicloudobs.ahjxjy.cn/CCB262151FF70754533754FDFC3319C8.png title=3-1.png alt=3-1.png/>
②
<img src=https://huaweicloudobs.ahjxjy.cn/83A1AEA490DB4820951AF907108F79C1.png title=3-2.png alt=3-2.png/>
③
<img src=https://huaweicloudobs.ahjxjy.cn/74B78581095A22F88DDA8A4CAA34704C.png title=3-3.png alt=3-3.png/>
④
<img src=https://huaweicloudobs.ahjxjy.cn/CC7D345862A2E284E535841FF229A55E.png title=3-4.png alt=3-4.png/>
【判断题】
<img src=https://huaweicloudobs.ahjxjy.cn/9D3D7615412973A3B3C7C9D3DE67D851.png title=3.png alt=3.png/>
①
正确
②
错误
【单选题】
<img src=https://huaweicloudobs.ahjxjy.cn/5F2C743DC46CDCDA93B776A820CB8E3B.png title=3.png alt=3.png/>
①
<img src=https://huaweicloudobs.ahjxjy.cn/51439F2090BF00DC24437CD20CFFA8CF.png title=3-1.png alt=3-1.png/>
②
<img src=https://huaweicloudobs.ahjxjy.cn/E57CC6F1A654B883AA62485D5889EA0A.png title=3-2.png alt=3-2.png/>
③
<img src=https://huaweicloudobs.ahjxjy.cn/9D33053A9B8D2DC52E2706604CF0A0BD.png title=3-3.png alt=3-3.png/>
④
<img src=https://huaweicloudobs.ahjxjy.cn/6E1E4F17794B1B4963ADD75D143A044E.png title=3-4.png alt=3-4.png/>
【判断题】
<img src=https://huaweicloudobs.ahjxjy.cn/0982661E5666B3C5C0555A92E972FD80.png title=3.png alt=3.png/>
①
正确
②
错误
