But it does not follow that the earth is spherical.

（主语从句）

1. 句子使用比较级结构，如：

   1. Benard Shaw remarks that we are more gullible and

      superstitious than we were in the Middle Ages.

   2. And much the greater part of our knowledge is at this level.

2. 句子使用强调结构，如：

1. But the truth is that it is energy that makes the world go round.

2. It was he who expected to be president.