Much to the couple’s comfort, their income is now double ________ it was five years ago. 

One advantage of fishing is ______ it can give you a lot of pleasure.

        others think about you isn’t important. The key is        you should be self confident.

—Haven't I seen you some place before?—Yes. That's ________ I don't go there anymore.

(2013·安徽，21)From space, the earth looks blue.This is ________about seventy­one percent of its surface is covered by water.