在西部大开发中,要对部分耕地“退耕还草、还林”。退耕农田的演替属于[ ]
A.初生演替
B.先是初生演替,后为次生演替
C.次生演替
D.先是次生演替,后为初生演替
答案:C
因式分x2-10x+25=______.
— Is the woman who walked past just now your teacher?
— Yes. She teaches ______ Chinese. [ ]
A. us
B. our
C. ours
D. we