Below the topsoil of the earth is the subsoil, _____ layer that contains stones mixed with a small amount of _____ organic matter.

A．a; the

B．the; the

C．不填; 不填

D．a; 不填

教室∶教师∶教材

A．法庭∶法官∶法警

B．舞台∶演员∶演戏

C．厨房∶厨师∶厨具

D． 军营∶士兵∶战场