"that"后面可以接多种成分，具体取决于它所引导的从句的类型和作用。以下是一些常见的情况：
定语从句
"that"作为关系代词，修饰前面提到的名词，并在从句中充当成分。例如：
The book that I am reading is very interesting.
The gril that is sitting under the tree is a good runner.
宾语从句
"that"引导的宾语从句用于陈述一件事，通常可以省略。例如：
I think that you can pass the exam.
I don't know what the word means.
状语从句
"that"可以引导目的状语从句、结果状语从句、原因状语从句、让步状语从句和条件状语从句。例如：
That car is red. （结果状语从句）
Although it was cold, we decided to go hiking. （让步状语从句）
名词性从句
"that"可以引导名词性从句，从句可以用现在分词做主语，谓语用三单。例如：
The problem that we need to solve is complex.
补语
"that"有时也用于引导补语从句，说明主语或宾语的品质、特征等。例如：
She is a girl that loves music.
根据具体的语境和句子结构，"that"后面可以接形容词、名词、代词、数词、介词短语、动词不定式（短语）、分词、定语从句或相当于形容词的词、短语或句子等。希望这些信息对你有所帮助。