4.
如图所示,在平行六面体\(ABCD-A_{1}B_{1}C_{1}D_{1}\)中,设\( \overrightarrow{A{A}_{1}}= \overrightarrow{a} \),\( \overrightarrow{AB}= \overrightarrow{b} \),\( \overrightarrow{AD}= \overrightarrow{c} \),\(M\),\(N\),\(P\)分别是\(AA_{1}\),\(BC\),\(C_{1}D_{1}\)的中点,则\( \overrightarrow{MP}+ \overrightarrow{N{C}_{1}}= =(\) \()\)