Tom, your room is too dirty. You must __________.
A:clean up it
B:clean up them
C:clean them up
D:clean it up
一元一次不等式组x-1≤01+12x>0的解集在数轴上表示出来,正确的是( )
用光照射某种金属时,从该金属逸出的光电子的最大初动能随入射光频率的变化图线如图所示,普朗克常量h=6.63×10﹣34 J•s,由图可知( )