依发电惯例，并励直流电动机的电压平衡方程可写成（ ）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/ba26910c3c8d43f3a8de1f46e82f946e.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/7609c39c539e4b11872334eef825e47e.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/a3c975313b99405da12dba5b1deba6eb.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/7e29646ee8764fc68d50ff9f89df6f6b.png" />

用莫尔法测定氯离子时，下列离子对测定结果没有干扰的是（ ）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/728e724646424bc29bfdde8843811830.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/2817f15029de441b8ade7fa47e0dbad4.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/8c7213f65d54485491577b8a9a8eadaa.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/a132f00401f8474eaf89e33d7d2113a6.png" />

偏心受压构件计算中，通过哪个因素来考虑二阶偏心矩的影响（ ）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/644d7258ea6b4667af5e583bc17ef89e.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/2a0b0bdd8f4641fc8e0e811f749223e2.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/5faa01da09ba40ffbf09b6e3c8a587db.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/be2081fe40ce490c975864d1cb9b2cb4.png" />

设r为接收机输入端信噪比，则2ASK调制系统相干解调的误码率计算公式为 ( ) A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/38cb16482933407692ae88aed02778f1.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/338c69dd51ba430287f982fc49eb0bac.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/1ee602edef494b56a6c3486101d45d47.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/1107dead25434878a02829cfe0d6c8fb.png" />

混凝土强度等级由立方体抗压试验后的( )。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/bf4e3c08bb664f88a72fad7dbd80223b.png" />确定 B: 平均值μ确定 C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/3b93a3139951423b9b3441c7f14a5c46.png" />确定 D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/dfaa321c576b414e91a6e7fca8060fbf.png" />确定