合同当事人双方并不相互享有权利、负有义务的合同,称为( )
公元前5世纪希腊人希波克拉底曾把人的气质分成( )、黏液质、胆汁质和抑郁质四种类型,但不很科学。
Choose the closest paraphrased version after the following sentence or the italicized part.
Different friends fill different niches in each person's life.( )