(1) $\int e^{x+e^{x}}dx= \underline { \quad \quad \quad }$.
(2)$ \int \dfrac {e^{x}dx}{2+e^{2x}}=\underline { \quad \quad \quad }$.
(3) $\int \dfrac {e^{x}}{ \sqrt {e^{x}-1}}dx=\underline { \quad \quad \quad }$.
$\text{A.}$
$\text{B.}$
$\text{C.}$
$\text{D.}$