按不同诊断目的选择最能表征设备状态的信号，对该类信号进行全面监测，并将其汇集在一起形成一个设备状态信号子集，指的是故障诊断基本步骤中的( )。
A．状态识别
B．特征提取
C．信号检测
D．诊断决策
参考答案：C
解析： 按不同诊断目的选择最能表征设备状态的信号，对该类信号进行全面监测，并将其汇集在一起形成一个设备状态信号子集，指的是故障诊断基本步骤中的信号检测。
| 完形填空。 | ||||
| A man was walking along the street when he saw a woman struggle (奋力) with a large box. It was half in and half 1______ of her car. He was a helpful kind of man, so he went up to the woman and said, "Let me give you a hand with that box. It looks very 2______." "That's very kind of you," the woman said."I'm having a lot of 3______ with it. I think it's struck (卡住)." "Together we'll soon move it," the man said. He 4______ into the back seat of the car and took hold of the other end of the box. He said, "I'm ready." And he began to 5______ hard. For several minutes the man and the woman struggled with the box. Soon they were 6______ in the fact. "Let's rest for a minute," the man said. "I'm sorry, but it 7______ stuck." A few minutes later, the man said, "Let's try again. Are you ready?" 8______ of them took hold of the box again. "One, two, three!" the man said, and they went on with their struggle. At last, when they were very tired, the man said, "You are 9______. It really is stuck. I don't think there's 10______ we can get it out of the car." "Get it out of the car!" The woman cried. "I'm trying to get it in!" | ||||
|
某同学拟定了以下实验方案，来确定一批合金废料的成分并加以回收利用。
请回答下列问题：
（1）从上述信息可确定该合金中一定含有Fe和____（填化学式）。
（2）“试剂a”是一种不引入杂质的绿色氧化剂，该氧化剂的化学式为____；滤渣D、稀硫酸和试剂a总反应的化学方程式为 。
（3）若反应①产生的气体是H2，则验证滤液A只含NaAlO2、不含Na2SiO3的方法是：取少量滤液A于试管中，滴加 。
Na2SiO3溶液与过量的CO2反应的离子方程式为 。
（4）取质量均为13．2g的滤渣B四份，分别加入相同浓度，不同体积的稀HNO3充分反应，标准状况下所生成的NO（设还原产物只有一种）体积与剩余固体金属的质量如下表：
| 实验编号 | ① | ② | ③ | ④ |
| 稀HNO3体积(mL) | 100 | 200 | 300 | 400 |
| 剩余金属质量(g) | 9．0 | 4．8 | 0 | 0 |
| NO体积(L,标况) | 1．12 | 2．24 | 3．36 | 4．48 |
②滤渣B中Fe的质量分数为____%（精确到0．1%）。