问题
多项选择题
高速公路所适用的面层类型包括( )。
A．沥青碎石
B．沥青混凝土
C．水泥混凝土
D．沥青表面处治
E．沥青灌入式
答案
参考答案：B,C
解析： 高速公路采用的路面等级是高级路面，适用的面层类型有沥青混凝土和水泥混凝土面层。
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高速公路所适用的面层类型包括( )。
A．沥青碎石
B．沥青混凝土
C．水泥混凝土
D．沥青表面处治
E．沥青灌入式
参考答案：B,C
解析： 高速公路采用的路面等级是高级路面，适用的面层类型有沥青混凝土和水泥混凝土面层。
Scientists think that there has been life for__31_ of years. However we haven’t found life on other planets _32_ . The earth is a planet and it _33__ around the sun. Seven other planets also go _34_ the sun. The sun and its planets are __35 the solar system. The solar system is a small part of our galaxy. Scientists __36_ lots of spacecraft to look at other planets in the solar system, and some spacecraft have gone __37_ the solar system. However, no one __38_ any life in space yet. But why has no one from other planets sent us a message ? Have they tried to send _39_ to us ? _40_so many stars in the universe, are we alone, or is there life out there in space ? We don’t know.
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