注意：此部分試題請在答題卡2上作答。
47. Nowadays, Melissa Gray of the University of Wisconsin-Madison and her colleagues confirmed that almost all small dogs carry _______.
48. What possibilities can be inferred after Gray's team failed to look for the mutations in 17 grey wolf populations around the world?
49. The research, done by Gray's team, is based on the question that _______.
50. According to the result from the team's research, the early evolution of small size in dogs probably arose in _______.
51. Archaeologists pointed out that when agriculture started in Middle Eastern, small size animal became more desirable in ______.