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【简答题】
简述旅游业的概念?
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皮皮学刷刷变学霸
举一反三
【单选题】His research focused on the complex anatomy of birds in flight, and he based his flying machines on this analogy. (Para. 6)
A.
He carefully studied the shape and structure of birds and applied the principles of their flight to the design of his flying machines.
B.
When he designed his flying machines, he imitated birds in flight.
【单选题】His research focused on the complex anatomy of birds in flight, and he based his flying machines on this analogy.
A.
When he designed his flying machines, he imitated birds in flight.
B.
He carefully studied the shape and structure of birds and applied the principles of their flight to the design of his flying machines.
【单选题】His research focused on the complex anatomy of birds in flight, and he based his flying machines on this analogy. (Para. 6)
A.
When he designed his flying machines, he imitated birds in flight.
B.
He carefully studied the shape and structure of birds and applied the principles of their flight to the design of his flying machines.
【单选题】下列关于粗骨料说法错误的是( )。
A.
在水泥用量和水用量相同的情况下，碎石拌制的砼强度较高，流动性较大
B.
在普通混凝土中使用的粗骨料一般有卵石和碎石两种
C.
碎石表面粗糙，具有棱角，与水黏结性好
D.
卵石多为圆形，与水泥浆的黏结性较差
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