嘌呤核苷酸从头合成途径中先合成的前体是
A．AMPB．UMPC．IMPD．GMP
参考答案：C
---Can you tell me ____?
---With Lucy’s help.
A．when you did it so well
B．when did you do it so well
C．how you did it so well
D．how did you do it so well
该公司共有管理层级（）。
A．3层
B．4层
C．5层
D．6层
