Das Gerund - Subjekt oder Objekt

Ist das Gerund Subjekt oder Objekt im Satz?

1 Skiing is fun in winter.
2 The pupils hate doing homework in the afternoon.
3 My dad loves cleaning my bike.
4 Swimming keeps you fit!
5 I prefer running.
6 Opening presents at Christmas is great.
7 Watching DVDs with friends is nice.
8 They enjoy baking cakes.
9 Cutting hair is great.
10 Mum loves painting our house.