① His house is twice as big as mine.

= His house is as big again as mine.

② This is twice the length of that.

③ In grain, the Japanese farmer does about twice as well, and his yield of such fruits as strawberries is probably three times as great as the average in America.

④ It might seem that a country so small as Holland could not support a large population. Nevertheless, the country has about two thirds as many inhabitants as the state of New York which is four times as large.