\[Mu] = Input["Mean=249.45"];
\[Sigma] = Input["St.deviation=2.16"];
A1 = Input["A1=30"];
A2 = Input["A2=20"];
U = Input["U=254"];
L = Input["L=245"];
T = Input["T=250"];
Subscript[\[Lambda], t] = (T - \[Mu])/\[Sigma];
Subscript[\[Lambda], l] = (L - \[Mu])/\[Sigma];
Subscript[\[Lambda], u] = (U - \[Mu])/\[Sigma];
k1 = A1/(T - L)^2;
k2 = A2/(T - U)^2;
\[CapitalPhi][u_] = \!\(
\*SubsuperscriptBox[\(\[Integral]\), \(-\[Infinity]\), \(u\)]\(
\*FractionBox[\(1\),
SqrtBox[\(2 \[Pi]\)]]
\*SuperscriptBox[\(E\), \(-
\*FractionBox[
SuperscriptBox[\(x\), \(2\)], \(2\)]\)] \[DifferentialD]x\)\);
\[CurlyPhi][v_] = 1/Sqrt[2 \[Pi]] E^(-(v^2/2));
CC = k1 ((\[Sigma]^2 + (T - \[Mu])^2) (\[CapitalPhi][
Subscript[\[Lambda], t]] - \[CapitalPhi][Subscript[\[Lambda],
l]])
+ \[Sigma] (T - \[Mu]) \[CurlyPhi][Subscript[\[Lambda],
t]] + \[Sigma] (L - \[Mu]) \[CurlyPhi][Subscript[\[Lambda],
t]] -
2 \[Sigma] (T - \[Mu]) \[CurlyPhi][Subscript[\[Lambda], l]])
+k2 ((\[Sigma]^2 + (T - \[Mu])^2) (\[CapitalPhi][Subscript[\[Lambda],
u]] - \[CapitalPhi][Subscript[\[Lambda], t]])
- \[Sigma] (T - \[Mu]) \[CurlyPhi][Subscript[\[Lambda],
t]] - \[Sigma] (U - \[Mu]) \[CurlyPhi][Subscript[\[Lambda],
t]] - 2 \[Sigma] (T - \[Mu]) \[CurlyPhi][Subscript[\[Lambda],
u]]);
q = \[CapitalPhi][Subscript[\[Lambda], u]] - \[CapitalPhi][
Subscript[\[Lambda], l]];
C0 = CC/q;
SequenceForm["C=", CC]
SequenceForm["C0=", C0]
如下图：

这位同学你这满屏的Input是想干嘛？然后我姑且问一句你该不会是以为对于
L = Input["L=245"]
你什么都不用输，只用直接点确定就可以让L被赋上245了吧？如果你确实是这么想的，那么，请仔细看看Input的帮助，不要臆测函数的语法。