Question

now ,at nowwhat are you doing now?这里的now为什么不用介词另外,at now 和no

Answer 1

因为now在这里是【副词做状语,副词前面不能加介词】.用法与here,there想似.比如：

We are here. 而不是We are at here.

没听说过at now的形式.now作副词的时候不能在前面加介词.