①—Is she seven?
—No, she isn't. She's eight.
②— Is she ten?
—Yes, she is.
③— Is she nine?
— Yes, she is.
④—Is she nine?
—No,she isn't. She's seven.
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下列有关化学用语表示正确的是
某自西向东流的河流,水流对南岸侵蚀严重,且一年有两次太阳直射现象,则该河流位于( )