These are our motives for doing it.选择一词替换motives.

1.
1)reason:a cause or an explanation for something that has happened or that somebody has done; a fact that makes it right or fair to do something
2)motive:a reason that explains somebody's behaviour
3)target:a result that you try to achieve:
2.汉语对应的词语
1)reason 原因,理由
2)motive 动机,目的
3)target 目标,对象
3.各词英语的搭配规律
1)target,
a target of sth
a target that ...
a target to do
2)reason,
reason for doing sth
reason for sth
reason to do sth
...
3)motive
motive for (doing)sth
motive in doing sth
总之,从意义上看,reason 和motive 是近意词;而target 与这俩词的意义差异甚远;
从target 习惯上接的修饰结构来看,a target of sth,a target to do 更合适.