His name was on the _____ of my tongue, but I just couldn't recall it.

A．end

B．point

C．edge

D．tip

盐酸布桂嗪（）。

A．结构中含有哌嗪环

B．结构中含有噻吩环

C．结构中含有环丁基

D．结构中含有噻唑环

E．结构中含有芳伯氨基