【要点归纳】
1. that 与whether(if)的用法区别
（1）that本身无意义，只起引导从句的作用，不在从句中充当任何句子成分。通常情况下，介词后不与that—从句连用，但是在except that（除…以外，只是）、in that（因为；在于）中可与that从句连用。
例句：① The problem is that they can’t get here early enough.
② Your article is good except that there are some spelling mistakes.
