I don't like it when mathematicians who know much more than I do can't express themselves explicitly.

Source: Tatoeba

People who can express their thoughts in a clear-cut way are very straightforward.

Source: Tatoeba

He sometimes has trouble expressing his opinions.

Sometimes he has difficulty being articulate about his views.

Source: Tatoeba

Three fourths of the earth's surface is covered with water.

Source: Tatoeba

Express yourself as clearly as possible.

Source: Tatoeba