People have planted a great many trees in order to________ wind and sand in the desert.
Come and see me whenever ___________.
Tom raised his handsto say something, but he remained silent in the end.
Not until the early years of the 19th century ________ what heat was.
_______ in a friendly way, their quarrel came to an end.
I sight of an empty seat at the back of the bus and went directly there. A. lost B caught C. looked D. took