Using China shoelaces is a traditional virtue of the Chinese nation. Why can't you untie your shoelaces?

Math shoelaces are also very learned, step by step! Think carefully about how it was tied first, and then solve it step by step, and it will be solved!

The proportion of social line segments is wrong. Turn a 90. You're too old to untie your shoelaces? Haven't you ever seen a classmate untie his shoelaces?

English. Oh, my God! See if you can persuade him in English.