当市场内二氧化碳浓度升高时，人体血液的pH会____ （填“升高”、“降低”、“不变”），影响人的健康。此时，自动天窗系统就会自动开启通风，使空气清新。

用课文原句填空。
①      　　         ，乌蒙磅礴走泥丸。（***《七律 长征》）
②落红不是无情物，  　  　　　　      。（龚自珍《己亥杂诗》）
③          　  　   ，铁马冰河入梦来。（陆游《十一月四日风雨大作》）
④商女不知亡国恨，         　　　     。（杜牧《泊秦淮》）
⑤《送杜少府之任蜀川》中“                 ，               ”两句，成为远离千山万水的朋友之间表达深情厚谊的不朽名句。
⑥杜甫《春望》中，“                ，                ”写感时伤怀、久别思家，即使鸟语花香，也悲伤惊心。

“临渊羡鱼，不如退而结网。”要想在考试中取得理想的成绩，关键是（    ）

    Once upon a time, there was a very young mouse who had never seen anything of the world. He almost got into trouble the very first time he went out. This is the s____ he told his mother about his adventures.

     “I was walking along very quietly when I saw two strange creatures（生物）. One of them had a very kind look, but the other was the most frightening monster you could i____ 

     “On top of his head and in front of his neck, there were pieces of red meat. The moment he saw me, he o____ his mouth as if he wanted to swallow me. Then he let out a roar that frightened me almost to death.”

     “I wanted to make friends with the pretty creature because it looked s____good and gentle. He had thick and smooth fur and a gentle face. His eyes were bright and shining. As he looked at me, he w____ his fine long tail and smiled.

     “My son,” said the mother mouse, “that gentle creature you saw was the cat. In fact the cat eats us. Under his k____appearance, he was against every one of us. The other was nothing but a cock who wouldn't be h____ to you at all. So you're lucky, my child. ”