题目内容
【题目】下列物质中属于混合物的是( )。
A.氮气 B.二氧化碳
C.空气 D.氧气
【答案】C
【解析】
试题分析:空气是含有多种气体的混合物,没有独立的化学符号。
【题目】D
A little dog stands near an old well(井). He stands there all morning. "wow-wow!" the little dog barks(吠叫). Bob hears him all the morning. 1 "Why do you stand here, little dog?" he asks. 2 The little dog looks at him. "Bow-wow-wow!" he barks again. 3 "Come here, Frank." He says. "A dog wants to tell us something." Ten minutes later, Frank arrives. 4 They see only a bone(骨头).
"This is what the dog wants to tell us," says Frank. 5 The dog is very happy and runs away.
根据材料内容,从下面五个选项中选出能填入文中空缺处的最佳选项,使短文意思通顺、内容完整,并将其标号填写在下面题号后的横线上。
A. Bob calls his brother Frank.
B. Then Frank gives the dog a bone.
C. At last Bob goes to the well.
D. "And what are you barking at?"
E. They look down into the well.
【题目】 This is the bike __________ my mother bought yesterday.
A. that B. who C. whom D. what
【题目】Art is _____ interesting subject.
A. a B. an C. the
【题目】
【1】watch, Tom, in, evening, the, doesn’t, TV
____________________________.
【2】favorite, what, is, your, sport
____________________________?
【3】because, art, like, I, it, interesting, is
_____________________________.
【4】he, have, does, on, Monday, geography
_____________________________?
【5】music , subject , favorite , is , his
【题目】下列关于空气成分的叙述正确的是( )。
A.空气中氮气和氧气的体积比约为4∶1
B.空气的成分按质量计算,氮气占78%,氧气占21%
C.从液态空气中能分离出氮气,不能分离出氧气和稀有气体
D.空气中含量最多且性质又不活泼的是稀有气体
【题目】用符合题目要求的序号填空:
①氧气;②空气;③二氧化碳;④二氧化硫;⑤五氧化二磷;⑥四氧化三铁。
(1)通常状况下无色、无味的气体是________;
(2)有刺激性气味并且污染空气的气体是________;
(3)属于黑色固体的是________;
(4)支持燃烧的气体是________;
(5)属于白色固体的是________。
【题目】 —I’m very __________ today because I have too much homework to do.
—Really? That sounds boring.
A. relaxing B. busy C. free D. cool
【题目】生活中常见的下列物质,不属于溶液的是( )。
A.糖水 B.蒸馏水
C.碘酒 D.汽水