1）But as far as the drug culture that they used to talk about, it's not as heavy as it was back ten years ago.

【答】back 是副词，可以表示“在后的位置”，也可以表示“追溯先前的时间”。本句指时间，修饰 ten years ago，起强调作用。去掉也可，意思没有太大变化。

2）These ideals were nurtured in me as far back as I can remember.

【答】back 也是副词，也表示“追溯先前的时间”。修饰far，起强调作用。去掉也可，意思没有太大变化。