Clue | Length | Answer |
---|---|---|
Was busy developing systems underground | 7 letters | subways |
Underground transit systems | 7 letters | subways |
US Underground trains | 7 letters | subways |
London's Underground and Paris's Metro, for example | 7 letters | subways |
U-boat has means to make tunnels underground | 7 letters | subways |
Pedestrian tunnels | 7 letters | subways |
was busy making underpasses | 7 letters | subways |
Transit systems | 7 letters | subways |
Tubes | 7 letters | subways |