— Don’t be too ______ with what you wear as a middle school student.

— Come on, Mom, stop being _____ on me all the time.

A．controversial, strict

B．particular, hard

C．considerate; keen

D．flexible; offensive

嘌呤碱基的C8来自于( )

A．N₅—CH＝NH—FH₄
B．N₅—CH₃—FH₄
C．N₁₀—CHO—FH4
D．N₅,N₁₀—CH₂—FH₄
E．N₅,N₁₀＝CH—FH₄