Is that _______ UFO in the sky(天空中)

____ to everyone the importance and value of these historic sites, the government has strengthened regulations to protect them.

－Miss Jones once _________ music at Bardon School for ten years and now is an actress.－No wonder I often hear her sing in the gardeny

13. Our bad living habits will destroy the earth. Only by changing ________we live can we save the earth.

The child tiptoed quietly to the bird. __ into the forest when he was about to catch it.