______ birds use their feathers for flight, some of their feathers are for other purposes.
Once
If
Although
Because
Today we have chat rooms, text messages and email, but we seem _______ the art of communicating face-to-face.
_________ to too much sunlight will do harm to your skin.
()There is no greater pleasure than lying on my back in the middle of the grassland, _____at the night sky.
__________ the program , they have to stay there for another two weeks.
What worried the child most was _______ to visit his mother in the hospital.