When we think about the long process of our English study and the level of our mastery of this language that we have reached, we should say that the input and outputratio is too low.
想想我们学习英语的漫漫之路和我们对英语掌握的程度，应该说我们的投入与产出比太低了。
3
Respectively calculate different sizes and U-value of window's structure of different opening style to be an ideal basis for choosing the best input-outputratio.