While he was investigating ways t improve the telescope Newton made _______discovery which completely changed ____ man’s understanding of color.

A．a ,/

B．a ,the

C．/, the

D．the ,a

我国社会保障部门所提供的社会保险包括( )。 Ⅰ．社会养老保险 Ⅱ．社会医疗保险 Ⅲ．社会失业保险 Ⅳ．意外伤害保险

A．Ⅱ、Ⅲ

B．Ⅰ、Ⅱ、Ⅲ

C．Ⅰ、Ⅱ、Ⅳ

D．Ⅰ、Ⅱ、Ⅲ、Ⅳ