時間： when, while, before, after, since, until, as soon as
原因： because, since, as, now that
條件： if, unless, provided that, as long as
對比： although, even though, while, whereas
Power TOEFL
TOEFL practice tests and AI study tools.
TOEFL practice tests and AI study tools.
副詞子句：時間、原因、條件、對比。
時間： when, while, before, after, since, until, as soon as
原因： because, since, as, now that
條件： if, unless, provided that, as long as
對比： although, even though, while, whereas
Conjunction vs preposition is a TOP TOEFL question type. If S+V follows, use a conjunction.