For example, there are more than 150 kilometers of rivers under the streets

Câu hỏi :

 For example, there are more than 150 kilometers of rivers under the streets of London. Most have been covered over and, sadly, all that .......(28)...... is their names. Perhaps the greatest loss to the city is the River Fleet, a once great river which previously had beautiful houses on its banks. It now goes underground in the north of the city and flows into the River Thames by Blackfriars Bridge.