按生产力高低排序，正确的答案是 A.
热带雨林>亚热带季雨林>北方针叶林>冻原  B.
开阔大洋>河口>湖泊>大陆架 C.
温带草原>稀树草原>常绿阔叶林>北方针叶林 D.
长江流域农田>黄河流域农田>黑龙江流域农田>热带雨林

__________ was the first musical film to include an aud...

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The Broadway Melody B.
The Wizard of Oz C.
The 42nd Street D.
The Jazz Singer

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