(2013·安徽卷)From space, the earth looks blue. This is about seventy-one percent of its surface is covered by water.
―What can I do for you? ―I'd like to buy a present for my son, ________ at a proper price but of great use.
A long time ________ a person, which is really a truth.
five minutes before the last bus left, we arrived at the station.
________ is known to us is that time is limited and precious.
―I went to the beach and got plenty of rest and sunshine. ― You looked tired last time I saw you .