据相关研究,经过40min完全黑暗后,人眼对光的敏感性达到最高点,比黑暗前增加25000倍,将数据25000用科学记数法表示为( )
【解析】
【分析】科学记数法的表示形式为a×10n的形式,其中1≤|a|<10,n为整数.确定n的值时,要看把原数变成a时,小数点移动了多少位,n的绝对值与小数点移动的位数相同.当原数绝对值大于或等于10时, n是正整数;当原数的绝对值小于1时,n是负整数.
【详解】解:将数据25000用科学记数法表示为2.5×104,
故选:B.
【点睛】此题考查科学计数法,科学记数法的表示形式为a×10n的形式,其中1≤|a|<10,n为整数.
据相关研究,经过40min完全黑暗后,人眼对光的敏感性达到最高点,比黑暗前增加25000倍,将数据25000用科学记数法表示为( )
If a man ______succeed, he must work as hard as he can.
Travellers ____our country enjoy the beautiful sights in Beijing, Hangzhou and many other places of interest.
We haven`t had any success_______.
﹣2的相反数是( )
The number of people invited____fifty, but a number of them _____absent for different reasons.
The flower is beautiful.
____________
Are you going there withthem ?
If you go,__________.
He is known to the world and has a lot of friends_______
_____your help, everything in the room is in good order now.