A:所含共用电子对数目为( a7 +1)NA
B:所含碳氢键数目为 aNA7
C:燃烧时消耗的O2一定是33.6a/14L
D:所含原子总数为 aNA14
This is 3-D printer. And this is an artificial (人工的) ear. Can you believe that scientists printed this artificial ear by this 3-D printer?
四边形ABCD是菱形,对角线AC,BD相交于点O,DH⊥AB于H,连接OH,∠DHO=20°,则∠CAD的度数是. ( )