Add commas to make non-defining relative clauses.
1 Last Christmas when we were on holiday
wh
it snowed twice.
2 My sister, who loves cooking, showed me how to
make pizza.
3 Spain where we go most summers/is one of my
favourite places.
4 Social networks/which are becoming more and
more popular, can be a good way to stay in touch.
5 My friend, whose brother is friends with my brother,
lives near me