图示结构用矩阵位法求解时，等效结点荷载列阵为：（）<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/97ca40c3ee6b4d67a2506e645b72a36e.png"> A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/e86f0ab977d94e67aabeb21f165ac815.png"> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/02fd4eb6cde249668ff035aa6f433ae5.png"> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/bb9ecf1cf72541419a4811205bdbed29.png"> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/d4eb9af1d0b744a388f1aa794e44f2d5.png">

单元刚度矩阵中元素<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/4b8d3c048bf344ea8cb72564e50f8b96.png">的物理意义是：（） A: 当<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/799278dd2f3c446b92ad68711d98763e.png">时引起的<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/4c8756cce17b474f8088c7e45544c233.png">相应的杆端力 B: 当且仅当<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/799278dd2f3c446b92ad68711d98763e.png">时引起的与<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/4c8756cce17b474f8088c7e45544c233.png">相应的杆端力 C: 当<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/2c2e6d24cad2454aa084e058690fa153.png">时引起的与<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/e9f5dfcac2cf4330a3a9a1d9ade1c07a.png">相应的杆端力。 D: 当且仅当<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/2c2e6d24cad2454aa084e058690fa153.png">时引起的与<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/e9f5dfcac2cf4330a3a9a1d9ade1c07a.png">相应的杆端力

下列关于极值命题中正确的是（） A: 若<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/66e36e20da3f43e9bbd9ce0f42dcbe28.png">，则<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/9d60dd3351b54052b4f4afe27423a0e7.png">必是<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/53f1ecb5821b44f1a56bbc836e49d9b7.png">的极值点 B: 若<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/0a40a2ad34e649e3b999f776e8fe1919.png">，则<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/9d60dd3351b54052b4f4afe27423a0e7.png">必是<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/53f1ecb5821b44f1a56bbc836e49d9b7.png">的极值点 C: 极大值一定大于极小值 D: 若<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/31b1a07ab57347febde3751859364dfb.png">存在且<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/9d60dd3351b54052b4f4afe27423a0e7.png">是极值点，则必有<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/66e36e20da3f43e9bbd9ce0f42dcbe28.png">

图示刚架,结点A承受力偶作用，EI=常数。用力矩分配法求得AB杆B端的弯矩是：（）<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/7f7f4973567d4fe1bba22dcfda90576b.png"> A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/924668c9b6164abf9ce5f8408ce20881.png"> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/7138e815e3484afc811e172c08c9c5ed.png"> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/e69f09485ad04e40851c731afb2381a2.png"> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/33f68a0494134087b303dd17cfaca7b1.png">

计算机控制系统中，若被控对象传递函数为<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/449150d9457a43b98c14899c6ffa5b27.png" >，设采样周期T=1s，则其广义被控对象的脉冲传递函数为（）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/eda76ecd0c754547a9d40ec652dd6389.png" > B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/950619299fc9457cab633a4abf11df94.png" > C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/f1b3a243951e47f0965e825c0ef3d0d8.png" > D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202007/817b81563181439e8e54ea1de38e039f.png" >