20．16．Where did Bob's parents go that night？ A．They went to a supermarket． B．They went to see a friend． C．They went to see a movie． 17．When did Bob smell anything bad？ A．Just before his parents left． B．When he was reading a magazine． C．When he was doing homework． 18．What did Bob first want to do when he smelt something bad？ A．To leave the house． B．To call the firemen． C．To call his parents． 19．What did Bob do after he called the firemen？ A．He ran out quickly． B．He telephoned his parents． C．He went to put away his things． 20．How soon did the fire go out after the firemen came？ A．In a few seconds． B．In ten minutes． C．In half an hour．
