单词竞猜（根据给出的单词意思解释，正确写出单词）
___________ the choice between two mutually exclusive possibilities.
___________uncertain; hesitant.
___________ to break the continuity or uniformity of sth.
___________to make or become sharp or sharper.
___________large in degree, kind, or quantity.
___________of or relating to an earliest or original stage or state.
___________to keep in perfect or unaltered condition; maintain unchanged.
___________intended for, applying to, or acting on a particular thing.
___________of, characterized by, based on, or constituting a system.
___________having a whirling sensation and a tendency to fall.