题目1单选题
如图所示超静定结构,选择图示力法基本体系,力法方程中的自由项<img src="https://tihai-oss-cloud.itihey.com/img/d81fd547ecbbcf828765140fdaf37836.png">等于( ).<img src="https://tihai-oss-cloud.itihey.com/img/d024ca0c5d4627825641108e4ae1ff3b.png">A. <img src="https://tihai-oss-cloud.itihey.com/img/58841f98f9e1790e40a64f77d7d5ee72.png">l<img src="https://tihai-oss-cloud.itihey.com/img/1aa667a850576a9cd4aa7e5abd8ab51a.png">B. -l<img src="https://tihai-oss-cloud.itihey.com/img/1aa667a850576a9cd4aa7e5abd8ab51a.png">C. 2l<img src="https://tihai-oss-cloud.itihey.com/img/1aa667a850576a9cd4aa7e5abd8ab51a.png">D. l<img src="https://tihai-oss-cloud.itihey.com/img/1aa667a850576a9cd4aa7e5abd8ab51a.png">