Question on completeness of sufficient statistic.

Question

Let $X_1,X_2,X_3....X_n$ be a sample from density $N(\theta,\theta^2)$ then the statistic $T=(\sum_{i=1}^n X_i,\sum_{i=1}^n X_i^2)$ is sufficient how do i check for completness in two dimensional space? I don't know how to to compute $E(g(x))=0$. Please someone tell me.