Who или which
4)The jobs (Who/which) he did in his young years were all very interesting.
5) The mice (who/which) live under the floor get out at night.
6) The man (who/which) married my sister is my good friend now.
7) The place (who/which) we visited last summer was very beautiful.

4which5which6which7which

4) The jobs (which) he did in his young years were all very interesting. 5) The mice (which) live under the floor get out at night. 6) The man (who) married my sister is my good friend now. 7) The place (which) we visited last summer was very beautiful.