Solution
= Solution
The <short exact sequence> of $G$-modules induces the <long exact sequence in group cohomology>
$$
0\to H^0(G,M_1)\to H^0(G,M_2)\to H^0(G,M_3)
\xrightarrow{\delta}H^1(G,M_1)\to H^1(G,M_2)\to\cdots.
$$
= Solution
The <short exact sequence> of $G$-modules induces the <long exact sequence in group cohomology>
$$
0\to H^0(G,M_1)\to H^0(G,M_2)\to H^0(G,M_3)
\xrightarrow{\delta}H^1(G,M_1)\to H^1(G,M_2)\to\cdots.
$$