社会必要劳动时间决定商品的（）

单色光垂直入射到每毫米500条刻痕的光栅上．若入射光波长为5.0×10-7m，求第二级主极大的衍射角；

Thisscientistwasawardedwithseveraltitlesforhis________(accomplish)inbiology

Janeisrestless;sheis_____animportantphonecallfromherparents.

Ifyouhavedifficultylocatingaparticularbook，pleaseaskourlibrariansfor___(assist).