介词短语与名词搭配 — 英语情景题

情景对话：Lily 在教室里帮 Sam 找东西。请根据每行对话中的位置提示，用正确的介词短语补全空缺处。 Lily: Sam, where is your English book? Sam: Look, it is (1)________.（在课桌下面） Lily: Oh, I see it. And where is your ball? Sam: My ball? It is not under the desk. It is (2)________.（在椅子上） Lily: OK, I found it. Now, where is your pencil? Sam: My pencil is not on the chair. It is (3)________.（在书包里）