[填空题]
The following diagram shows the parallelogram AB394d gr/k4nbp c1tavgCf ;d7fr t(hji)es-p- zD.
Let E denote the midpoint of [B D], $\mathbf{p}=\overrightarrow{\mathrm{BA}} $ and $ \mathbf{q}=\overrightarrow{\mathrm{BC}} $. Find each of the following vectors in terms of $\mathbf{p}$ and $\mathbf{q}$ .
1. $\overrightarrow{\mathrm{AC}}$ ;
2. $\overrightarrow{\mathrm{BE}}$ ;
3. $\overrightarrow{\mathrm{AE}}$ .