题目内容：

Which is much___(far) from the earth,the sun or the moon?
which of the three inventions is___(useful) one?
when you telephone him last night,I ___(watch) TV.

优质解答

1.farther 两者比较用比较级
2.the most useful 三者比较用最高级
3.was watching 昨晚你打电话时我正在看电视.过去进行时