For a lattice spacing of 0.6 nm and the X-ray wavelength of 0.7 nm, the Bragg angle is (in deg):
对于晶格间距为0.6nm，x射线波长为0.7nm，布拉格角为（以度为单位）：
A、35.7
B、37.5
C、39.8
D、42.3