【单选题】— What did you do this morning? — I went _____. [ ]
【简答题】元组解包的概念?举例说明?(每问 3 分,共 6 分)
【简答题】厚度为 2.0m 的烟气层, 测得 有 30% 的光穿过,计算单位厚度上烟气的光学密度为( )及烟气的消光系数为( ) m -1 。结果保留三位有效数字,不用写单位。
【单选题】What is special about the shop's service?
A.
The shop guarantees the battery for a year.
B.
The man will clean it at no extra charge.
C.
The man can repair watches very quickly.
D.
The shop is offering a special discount.
【单选题】—What’s Jack up to in the shoe shop? He’s there for ages. —It’s ______ that he hasn’t decided which pair to buy.
【判断题】聚光比是指使用光学系来聚集辐射能时,每单位面积被聚集的辐射能量密度与其入射能量密度的比。( )
【单选题】纳米技术在研究电学材料、光学材料、高密度材料方面有广泛的应用前景,纳米是下列哪种物理量的计算单位