We should have a sense of responsibility to do something to help ____ poor whenever they are in___ trouble.

A．不填; the

B．the; the

C．the; the

D．the;不填

第一次把圆周率的数值计算到小数点后第7位数字的数学家是[ ]

A．祖冲之

B．刘徽

C．贾思勰

D．郦道元