问为什么不能选择基础网络啊？只有私有网络一个选项？

private void Test1()

{

    string test1 = string.Empty;    

    string test11 = test1;

}

private void Test2()

{

    string test2 = "";    

    string test22 = test2;

}

.method private hidebysig instance void 

          Test1() cil managed

{

  // Code size       10 (0xa)

  .maxstack  1

  .locals init ([0] string test1,

                [1] string test11)

  IL_0000:  nop

  IL_0001:  ldsfld     string [mscorlib]System.String::Empty

  IL_0006:  stloc.0

  IL_0007:  ldloc.0

  IL_0008:  stloc.1

  IL_0009:  ret

} // end of method Form1::Test1

.method private hidebysig instance void 

        Test2() cil managed

{

  // Code size       10 (0xa)

  .maxstack  1

  .locals init ([0] string test2,

                [1] string test22)

  IL_0000:  nop

  IL_0001:  ldstr      ""

  IL_0006:  stloc.0

  IL_0007:  ldloc.0

  IL_0008:  stloc.1

  IL_0009:  ret

} // end of method Form1::Test2

        string test1 = string.Empty;

0000003a  mov         eax,dword ptr ds:[022A102Ch] 

0000003f  mov         dword ptr [ebp-40h],eax 

        string test11 = test1;

00000042  mov         eax,dword ptr [ebp-40h] 

00000045  mov         dword ptr [ebp-44h],eax 

        string test2 = "";

0000003a  mov         eax,dword ptr ds:[022A202Ch] 

00000040  mov         dword ptr [ebp-40h],eax 

        string test22 = test2;

00000043  mov         eax,dword ptr [ebp-40h] 

00000046  mov         dword ptr [ebp-44h],eax