call不是情态动词。
A number x is called an almost upper bound of a .数X称为A的殆上界。
The opening of the iris is called the pupil .虹膜的开口处叫做瞳孔。
Then it is often called survivor growth .为此，常称它为生存木生长。
He answered the call of duty and enlisted in the army .他应征入伍。
