He wrote a letter ______ he explained what had happened in the accident.

Stephen Hawking believes that the earth is unlikely to be the only planet ________ life has developed gradually[ ]

_____ a report from WWF, the global warming has greatly _______ wildlife on the earth,destroying or damaging the habitats they are living in.[ ]

Eat ______ meat and take _______ exercise, and you will be healthier.

Most British believe that there has never been a more splendid opening ceremony than_______ of the London 2012 Olympic Games.