这只漂亮的北极熊大约重400kg

1 about,in weight
2 The bear weighs about 400 kg
== The bear is about 400kg in weight
3 sb weighs 70 kilogrammes
sb is 70 kilogrammes in weight
sb is 70 kilogrammes heavy
4 People have badly polluted this river .
= This river has been badly polluted by people.
5 This is the village in which we live
== This is the village WHERE we live

1. is about 400 kg weight
2.
3. He weighs 400 kg

4. The water is polluted by ash