题目

浅海中海藻、节肢动物、鱼类、微生物等生物生活在一起，这些生物构成了 A．生物圈           B．生态系统         C．群落         D．种群 答案： C--Thank you very much ________ helping me to repair my old computer. --That's all right. Thanks ________ your letter, I can come in time and repair it for you. [　　] A．for; forB．to; toC．to; forD．for; to