「に」と「で」の使い方
「ベッドで寝る」と「ベッドに寝る」とどっちが文法的にいいですか？
「ベッドに寝る」というのは「ベッドに入って寝る」の短くした表現ですか？

Question

Answer

Generally we say 'ベッドで寝る’。If you want to emphasis on 'bed', then you can say 'ベッドに寝る’。
For example, when you go to the hospital, a nurse says ’ベッドに寝てください’。
’ベッドに寝る’ doesn't short sentence of ’ベッドに入って寝る’.But normaly we think it means ' ベッドに入って寝る’。I hope you can understand it！

Answer

会議は　3時に終わります（The meeting will end at 3 o'clock）
会議は　3時で終わります ( The meeting will end within 3 hours)
で　 describe a stitch of time 
に    point in time

教室で　本を　読みます(dynamic state usedで)
図書館には　いろいろな分野の　本がある（static state usedに ）

if you know this ,it will be easy to find out the different between ni and de ~

Answer

It's all here:

http://www.guidetojapanese.org/learn/grammar/verbparticles

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