用力法计算图示结构时，不能作为基本结构的是图（   ）

<img src、"http://gansu.ouchn.cn/pluginfile.php/61594/question/answer/222283/5/246954/001-a.jpg" alt="" width="150" height="150">

<img src、"http://gansu.ouchn.cn/pluginfile.php/61594/question/answer/222283/5/246955/001-b.jpg" alt="" width="150" height="150">

<img src、"http://gansu.ouchn.cn/pluginfile.php/61594/question/answer/222283/5/246956/001-c.jpg" alt="" width="150" height="150">

<img src、"http://gansu.ouchn.cn/pluginfile.php/61594/question/answer/222283/5/246957/001-d.jpg" alt="" width="150" height="150">