The teacher had to spend her weekend marking all the tests.

… a reminder of how many factors, unknown to or unrealised by the passenger in the train, may be having their effect on its running. (not realised may have been better here)

English people are travel junkies, but Americans hardly ever leave their state.

[…] Each weed / That grows about her grave I know; They spring / With gaudless flowers, year after year the same: […]