Ｂｌｏｗ ｔｈｅ Ｂｏｏｋ Ａｗａｙ等６則
2005-04-29 00:00:00
科學大眾(中學) 2005年8期
Blow the Book Away
What to do:Loop the two pieces of string around the book and knot them.Then tie the loose ends of the strings to the rod of the wooden hanger so the book swings freely，as in the illustration.
