later ,people began to train___like horses and camels and used them for_____填上两个适当的词.

问题描述:

later ,people began to train___like horses and camels and used them for_____填上两个适当的词.

Later,people began to train (animals,动物) like horses and camels and used them for (riding,骑).
后来,人们开始训练像马和骆驼这类的动物,用于骑坐.