题目

Having returned from her round trip, the angry woman stood outside the ticket office of the station. “The railway owes (欠债) me $12,” she said to Harry Jenks, the young man working at the    36  . “You sold me a ticket   37   May 22nd, but there was no ship from Jersey that night. So my daughter and I had to stay in a hotel. It   38   me $12.” Harry was   39  . He remembered selling the woman a return ticket. “Come into the office, Madam,” he said politely. “I’ll just   40   the Jersey timetable for May 22nd. The woman and her little girl followed h在横线里写出每组数的最大公因数．13和7________　　　　　 15和21________　　　　　 18和54________　　　　　　 12和20________．