第二信使
参考答案：
细胞表面受体接受胞外信号后最早在胞内产生的信号分子。细胞内重要的第二信使有：cAMP、cGMP、DAG、IP3等。
--- Have you got ready for the meeting?
--- Not yet. We need ________.
A．three other chairs
B．other three chairs
C．another three chairs
D．three another chairs
Speaker A: Do you think you could keep the noise down a bitSpeaker B: ______
A．Yes, of course I could. I will turn it down a bit.
B．Oh, I beg your pardon. I think so.
C．Yes, sorry. Am I disturbing you
D．Sorry! Have I been keeping you awake
