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【简答题】
一片农田弃耕一年后杂草丛生,现已演替至灌木阶段。如果外界条件基本不变,且无人为干扰,将来有可能演替至森林阶段。请回答: (1) 该农田的演替进程比初生演替快,主要原因是 ________ 优越和植物繁殖体的存在。 (2) 从杂草阶段演替到灌木阶段,捕食关系很容易发生变化,其主要原因是 ________ 的种类和数量发生了明显变化。 (3) 图中曲线 a 、 b 中表示该群落中植物物种数变化的是 ________ 。 (4) 该农田在演替至森林阶段的进程中, ________ 阶段最易遭受外来物种的入侵而使占优势的物种发生变化;如果在灌木阶段遭遇一场火灾,烧掉了灌木下的草本植物,但对灌木影响不大,则演替进程 ________( 加快,基本不变 ) ;若演替至森林阶段,在广东省最有可能出现的森林群落类型是 ________ 。该农田的演替过程伴随着物质的积累,其中积累最多的是 ________ 元素。
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举一反三
【单选题】-Nice to meet you. -_____
A.
Fine, thank you.
B.
How are you?
C.
Nice to meet you, too.
D.
Thank you.
【单选题】Section D 听力原文： Listen to a talk given by an astronaut. Thank you. It's great to see so many of you interested in this series on 'Survival in Outer Space'. Please excuse the cameras--we're being video...
A.
To show a videotape on survival in outer space.
B.
To gain support for the space program.
C.
To describe her experience on space missions.
D.
To inform. the audience about the space suit.
【单选题】How are you?----______________
A.
How are you ?
B.
Thank you
C.
Fine, thank you.
D.
Good.
【单选题】Section A (1)
A.
It' s open at 9 a. m.
B.
Sorry, I have no idea.
C.
That's all right.
D.
Thank you
【简答题】Section D 听力原文： Thank you all very much for coming. I will try to be as brief as possible. As I expect you’ve got your rights on the refreshments set at the back of the room which will be served the m...
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