—It's so cold today.
—Yes, it's _____________ colder than it was yesterday.
A:some
B:more
C:very
D:much
次数
钩码重/N
动滑轮重/N
钩码上升
的距离/cm
弹簧测力计
的示数/N
弹簧测力计上升的距离/cm
机械效率
1
2
0.8
5
15
66.7%
4
1.7
\
3
6
家住北京的小强,暑期准备乘火车去上海旅游,他应选择哪条铁路线最合理( )