【单选题】【消耗次数：1】
He comes to see his parents [填空] three days.
①
every
②
both
③
each
④
one
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相关题目
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The letters for the boss __________ on his desk but he didnt read them until three days later.
①
were put
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He said that his sister ?[填空]been there one week before
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There is a variety of programs___________ one can see on every channel.
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that
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what
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which
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At the end of every term a schoolmaster____ on each of his pupils.
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tells
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reports
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He __________ five telephone calls to his parents.
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makes
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That day he ___________ his clothes before he came to see me.
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【单选题】
That day he ___ his clothes before he came to see me.
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He was such a ____ speaker that he held our attention every minute of the three-hour lecture.
①
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③
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随机题目
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下列事实不能用电化学理论解释的是（ ）。
①
铝片不用特殊方法保存
②
镀锌的铁比镀锡的铁耐用
③
轮船水线以下的船壳上装一定数量的锌块
④
纯锌与稀硫酸反应时，滴入少量硫酸铜溶液后速率加快
【单选题】
下列污染现象主要与<img class="kfformula" src="20200629/1593429156221829.png" data-latex="{NO}_{2}" width="40" height="25"/>有关的是（）。
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光化学烟雾
②
水体富营养化
③
温室效应
④
臭氧空洞
【单选题】
列污染现象主要与<img class="kfformula" src="20200629/1593437074992922.png" data-latex="{SO}_{2}" width="59" height="33"/>有关的是（）。
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酸雨
②
臭氧空洞
③
温室效应
④
光化学烟雾
【单选题】
除去<img class="kfformula" src="20200629/1593439477401116.png" data-latex="{CO}_{2}" width="47" height="31"/>中混有的少量<img class="kfformula" src="20200629/1593439477395990.png" data-latex="{SO}_{2}" width="52" height="33"/>气体，可选用试剂( )。
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品红溶液
②
澄清石灰水
③
饱和<img class="kfformula" src="20200629/1593439477463503.png" data-latex="NaH{CO}_{3}" width="84" height="35"/>溶液
④
溴水
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下列关于浓硫酸的叙述中，正确的是( )。
①
浓硫酸在常温下能够使铁、铝等金属形成氧化膜而钝化
②
浓硫酸在常温下可迅速与铜片反应放出二氧化硫气体
③
浓硫酸具有吸水性，因而能使蔗糖炭化
④
浓硫酸是一种干燥剂，能够干燥氨气、氢气等气体
【单选题】
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①
<img class="kfformula" src="20200623/1592891181453159.png" data-latex="{Fe(OH)}_{3};\, {Fe}_{2}{O}_{3}" width="157" height="32"/>
②
<img class="kfformula" src="20200623/1592891181971969.png" data-latex="{Fe(OH)}_{2};{Fe(OH)}_{3};{Fe}_{3}{O}_{4}" width="205" height="36"/>
③
<img class="kfformula" src="20200623/1592891181879323.png" data-latex="{Fe(OH)}_{2};FeO" width="136" height="33"/>
④
<img class="kfformula" src="20200623/1592891181551807.png" data-latex="{Fe}_{2}{O}_{3};Fe{(OH)}_{3}" width="161" height="31"/>