He was lost in the busy streets. But at last it was _______ of him to find the way home.

Science and technology are developing ______ quickly that some new electronic products are out-of-date within several months.

If there ______no buying and selling of animals, there ______no killing in nature.

I will take part in the quiz show next week. —_________.

Wehopetogetsuchatool ______heisusing.[ ]