When the Channel Tunnel opened, many people had high 1) (EXPECT). Instead of travelling for up to 3 hours by sea, the tunnel appeared to be an 2) (ATTRACT) alternative. However, the Channel Tunnel project ran into some unexpected 3) (DIFFICULT). For example, nobody had imagined that there might be a power 4) (FAIL), leaving the passengers stranded in the tunnel for hours. 5) (OBVIOUS), problems like this have been overcome and the tunnel now satisfies passengers' 6) (REQUIRE) for a fast and enjoyable journey.