four girls went to school every day by taxi .

　　one day one of the girls said,"there's a test this morning . let's get to school late

　　then we won't have to take the test ."

　　"what can we tell the teacher?" one of the girls said.he'll be angry . we'll need a good excuse moments ."

　　the girls though for several moments ,than one of them said ,"let's tell him that our taxi had a flat fire ."

　　"that's a good idea ,"the other girls said."we'll tell him that." they arrived at school an hour late . the test was finished .

　　"why are you late?"the teacher asked ."you missed the test."

　　"our taxi had a flat fire,"one of the girls said .

　　the teacher thought for a moment ,then he said ,"sit down ,one of you in each corner of the room ."

　　the four girls did this

　　than the teacher said ,"write on a piece of paper the answer to this question :which tire was flat?"