\[\boxed{\mathbf{961.}}\]
\[1)\ tg\ \pi + \cos\pi = 0 +\]
\[+ ( - 1) = - 1\]
\[2)\ tg\ 0{^\circ} - tg\ 180{^\circ} = 0 - 0 = 0\]
\[3)\ tg\ \pi + \sin\pi = 0 + 0 = 0\]
\[4)\cos\pi - tg\ 2\pi = - 1 - 0 = - 1\]