After running idasm, i found that
IL_0000: /* 02 | */ ldarg.0
IL_0001: /* 18 | */ ldc.i4.2
IL_0002: /* 8D | (01)000004 */ newarr [mscorlib/* 23000001 */]System.String/* 01000004 */
IL_0007: /* 0A | */ stloc.0
IL_0008: /* 06 | */ ldloc.0
IL_0009: /* 16 | */ ldc.i4.0
IL_000a: /* 72 | (70)00001B */ ldstr "Hello World by " /* 7000001B */
.....
there are some (01), (70), (04) and (0A). It seems pointing to something, actually what these means

Instruction of IL in PE File(01)(70)(04)(0A)?
Joshna
It's simply the table index to which the RID refers. 01 is the TypeRef table, 04 is Field, 0A is MemberRef and 70 is the value used for string tokens.