题目

_________ to take this adventure course will certainly learn a lot of useful skills . A . Brave enough students B . Enough brave students C . Students brave enough D . Students enough brave 答案：C用两支铅笔夹成一条狭缝，将眼睛津贴着狭缝并且让狭缝与日光灯管平行，可以看到美丽的彩色条纹。这种现象是A．光的干涉现象      B．光的折射现象C．光的衍射现象      D．光的偏振现象