普通双绕组降压变压器，一、二次侧额定值的关系是( )。
A: S1N=S2N,U1N>U2N,I1N>I2N
B: S1N=S2N,U1N>U2N,I1NS2N,U1N>U2N,I1N>I2N
C: S1N>S2N,U1N>U2N,I1N
A: S1N=S2N,U1N>U2N,I1N>I2N
B: S1N=S2N,U1N>U2N,I1NS2N,U1N>U2N,I1N>I2N
C: S1N>S2N,U1N>U2N,I1N
举一反三
- 2、双绕组降压变压器高压绕组的额定容量、额定电压、额定电流分别为S1N、U1N、I1N，低压绕组分别为S2N、U2N、I2N，它们之间的关系是（ ）。 A: S1N=S2N, U1N>U2N, I1N>I2N B: S1N=S2N, U1N>U2N, I1N<I2N C: S1N>S2N, U1N>U2N, I1N>I2N D: S1N>S2N, U1N>U2N, I1N<I2N
- 假设整型n已输入值。以下不能正确计算1*2*3*...*n的程序段是_______。 (1) for(i=1,s=1; i<=n; i++) s*=i; (2) i=1;s=1; while(i<=n) s*=i++; (3) i=0,s=1; do{ i++,s*=i; }while(i<=n); (4) for(i=1,s=1; ; i++) { s = s*i, if(i==n) break; }
- 当$|z|<0.5$时左边序列$x[n]$为 A: $[(\frac{1}{2})^n-2^n]u[-n-1]$ B: $[(\frac{1}{2})^n+2^n]u[-n-1]$ C: $[2^n-(\frac{1}{2})^n]u[-n-1]$ D: $[2^n+(-\frac{1}{2})^n]u[-n-1]$
- 中国大学MOOC: 下面代码执行后，变量s的值为______。 Dim i, n As Integer, s As String i = 2 : n = 12 : s = n & = Do Until n = 1 Do While n Mod i = 0 s &= i & * n = n i Loop i += 1 Loop s = Strings.Left(s, Len(s) - 1)
- 若有数组Dim a%(10)且每个元素有值，统计前一个元素大于后一个元素的次数，结果存放在变量n中。则下列语句正确的是___________。 A: Dim i%, n% For i = 1 To 10 If a(i) > a(i + 1) Then n = n + 1 End If Next MsgBox(n) B: Dim i%, n% For i = 1 To 10 If a(i) > a(i + 1) Then n = a(i) End If Next MsgBox(n) C: Dim i%, n% For i = 0 To 9 If a(i) > a(i + 1) Then a(i) = n + 1 End If Next MsgBox(n) D: Dim i%, n% For i = 0 To 9 If a(i) > a(i + 1) Then n = n +1 End If Next MsgBox(n)