First of all, for the limit of f(x)+g(x), we can cite some special cases.

For example, f (x) = 0 (x

f(x)= 1(x & gt； a)g(x)= 0(x & gt； answer

In this way, the limit of f(x)+g(x) at A is obviously 1, excluding A and C. .

Another example is f (x) = 0 (x

f(x)= 1(x & gt； a)g(x)= 2(x & gt； answer

In this way, f(x)+g(x) has no limit at A, and B excludes it. .

So it can only be D.