[单选] Rock石头 If you look around you， you can find some rocks very easily． Rocks are minerals and they are all from the earth． What colours of rocks can you see？ You can see silver， white，brown，gold， orange，blue， red， pink， black， and even rainbow-coloured rocks． There are many different colours of rocks on the earth． Why don"t you find those colours of rocks right now？I．Read and choose．阅读短文，选择正确的答案。1．What are rocks made of ？