(1) 生命单体 (2) 原始水生物 (3) 生物大分子 (4) 简单有机物 (5) 地球生物圈

A．4-1-2-3-5

B．3-2-4-5-1

C．4-3-1-2-5

D．3-4-2-1-5

—Oh, sorry, what did you say just now?  

—I asked _______.[ ]

A. Where he comes from                  

B. where did he come from

C. where he came from                  

D. when did he go