动物在生态系统中的角色是（    ）

    In February of 2005, Phil Belfiore was teaching one of Robert Frost's poems “Stopping by Woods on a Snowy Evening.” He liked it that he recorded it on his home answering machine, which would lead to one of the most unusual1of his life.

    When Phil returned from his vacation, he listened to his voice 2  One gentleman caller 3for dialing the wrong number. But, he added, he'd really 4the poem. Phil laughed and thought nothing more of it— 5the phone rang a few days later.

    Phil 6John's hollow voice immediately, who said sorry to7, but he was calling to hear the8again. The two men talked. It turned out that his brother's phone number was9from Phil's by one digit(数字), thus the wrong number. Before hanging up, Phil told John to 10anytime, whether to hear the poem or just to have a chat.

    That was 11 years ago. They've spoken on the phone a few times a month ever since. It is John who is 11the starter of most calls. However, Phil will ring if a long while has passed. Not 12  John has been in poor health. His special voice is just the 13of some heart trouble. They seem to always 14when there's been a big sports event. The man like to discuss 15most. John will also 16Phil on his life. Slowly, their conversations have grown much more 17  When asked what drew them together, Phil18that they were old friends. They planned to meet twice, but circumstances went19them. Their friendship is based on the simple act of picking up the phone. “My best friend is someone I've not yet met 20 ” says John. It's as simple as that.

准确称取某种铁的氧化物2.88g，用足量的CO进行还原，将生成的CO₂全部用足量的澄清石灰水吸收，得到沉淀4g，则这种铁的氧化物为（　　）

—Are those your books?

—____. They are hers.