106. The dangerous semicircle of a hurricane in the Northern Hemisphere is that area of the storm ______.

Let us construct, with the origin(原点) as center, a semicircle(半圆) of radius R.

In the Northern Hemisphere, if your vessel is in a hurricane’s navigable semicircle it should be positioned with the wind on the ______

下列哪些单词中含有表示half含义的前缀? A: biannual B: dialogue C: hemisphere D: semicircle