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一只标有“220V 1200W”的空调正常工作5h要消耗______kW•h的电能；1kW•h的电能可供“220V 40W”的节能灯正常发光______h．

答案

①∵P=

W
t
，∴空调消耗的电能为W=Pt=1.2kW×5h=6kW•h；

②∵P=

W
t
，∴节能灯正常发光的时间为t=
W
P
=
1kW•h
0.04kW
=25h．

故答案为：6；25．

补全对话，情景问答
给下列的问句选择对应的答句。
( ) 1. Where is your mouth?
( ) 2. Nice to meet you!
( ) 3. Happy Teachers' Day!
( ) 4. Good morning!
( ) 5. How are you?
( ) 6. What's your name?		A. Nice to meet you, too.
B. Here it is.
C. My name is Mike.
D. Very well, thanks.
E. Thank you.
F. Good morning!
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填空题

夜盲症是由于缺乏（）
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