若某系统的传递函数为G（s）=<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/40cffec1140048fda668f02b2697bfb6.png" >，则相应的频率特性G（jω）为（）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/b0edaaca759a4b96b2746d371ba37485.png" > B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/17d6f581231244c386888754b3bf178d.png" > C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/e5485f9797b64853b91ce68c4697ff2e.png" > D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201912/5330c18e71b94abdbeaeff937486d18a.png" >

反应H2(g)+Br2(g)→2HBr(g)的△r[img=104x98]17d609268cec96e.png[/img]与反应H2(g)+Br2(l)→2HBr(g)的△r[img=104x98]17d609269a5ade0.png[/img]相同。

从数字<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/2d61a913ea754ceab9283348404e99b8.png" >中任取两个不同的数字，则这两个数字之差的绝对值的数学期望为()。 A: 1 B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/7da33d3a3bd54a188acf94dfdbab4f56.png" > C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/e8d44a97a0d141198c56ce68511897c9.png" > D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/201911/fa3d4d77c7ea4487a9fd484134badc5e.png" >

（ ）下列两个反应的热效应相比，第 ② 个放热较多： ① H2 ( g ) ＋ Br2 ( g ) → 2 HBr ( g ) ② H2 ( g ) ＋ Br2 ( l ) → 2 HBr ( g ) A: 正确 B: 错误

考虑AR(2)模型<img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/9c19d336a086430cab947cf3a40c8047.png" />,则AR特征方程的根为（ ）。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/b8d42e894377426eaca4f3a382c0569c.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/cb2410db797c4dc5870eb9ab1dfae59e.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/505155f9e5654d3294291a0f104fd54f.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202105/ff900163e913414384b61dbd55a0c36e.png" />