The achievements of the greatest minds in science could never have been reached if it had not been for the patient and accurate work of hundreds of other people.

A．has it not been

B．if it had been

C．if hasn't been

D．had it not been

构成法学体系的是( )

A．法学的分支学科

B．法学的研究对象

C．法律的调整对象

D．法律现象的性质