A:30-24=6(颗)
B:30+24=54(颗)
C:54-24=30(颗)
D:54-30=24(颗)
We should give the children with ____ ____ a chance to show their skills.
水力发电中能量的转化情况是()
写出下列科学家的发现:
列文虎克;弗莱明;胡克