— There are so many trees on      side of the street.

—Oh, yes, and they are beautiful.[ ]

A. either

B. neither

C. both

D. all

假设是两个变量之间的关系假定，如假设“社会工作者应变能力越强，服务对象出现积极改变的可能越大”，属于( )。

A．肯定式假设

B．常规式假设

C．解释式假设

D．条件式假设

E．差异式假设