51.   The tunnel was an excuse.

52.   The tunnels themselves are undeniably impressive.

53.   There are tunnels that begin, then abruptly stop.

54.   These mud tunnels are the roads the termites make to get in and out of the house.

55.   Tunnels are the things that run under the river, except that these are more often called tubes.

56.   Tunnels are typically very costly to construct, the border patrol is always on the lookout for illegal crossings and airplanes and airports are carefully monitored.

57.   Tunnels have been located and, in some mansions, secret hiding areas have been revealed.

58.   Trucking executives say that tunnel is risky, because it features steep grades near its entrance.

59.   Tunnels are not the things that run between regular stations.

60.   Tunnels were steam-cleaned and graffiti scrubbed off.