A:功率大的机械比功率小的机械做功快
B:做功时间越长,机械功率越大
C:机械做功越快,机械效率越高
D:做功越多机械效率越高
Opening
Fees
Notice
Monday to Friday
10:00 a.m. – 6:00 p.m.
Adults(成人):$ 8.00
15 – 18: $ 6.00
8 – 14: $ 3.00
Under 8: free(免费)
1. Don't feed the animals!
2. Don't litter about.
3. Don't smoke.
4. Kids under 8 can't be alone
without parents.
Saturday to Sunday
8:00 a.m. – 8:00 p.m.
物理学研究中常常用到“控制变量法”、“等效法”、“类比法”等科学方法。在下列研究实例中运用了控制变量法的是( )