conj. Upon any less condition than (the fact or thing stated
in the sentence or clause which follows); if not; supposing that not;
if it be not; were it not that; except; as, we shall fail unless we are
industrious.
conj. 除非
prep. 除...之外
1. I won't go to the party unless you come with me.
如果你不和我一起去，我就不去那个聚会。
2. She won't finish her homework unless she focuses on it.
她如果不专注，就无法完成作业。
3. You can't enter the club unless you are a member.
你必须是会员才能进入俱乐部。