下列有关热机效率、燃料热值、物体内能的说法中，正确的是（　　）

A．热机所用燃料的热值越大，效率越高　

B．热机所用燃料的化学能转化成的内能越多，效率越高　

C．物体的内能越大，温度越高　

D．摩擦生热是利用做功的方式来增加物体的内能

I'm told that you are going to Canada to have a threemonth further study. Don't let such a good chance

to improve your English ________ through your fingers. [ ]

A. ski  

B. spread

C. slip  

D. skip