Grammar Point
to do something in advance
after the -te form of a verb
to leave something in a certain state, to keep something in a certain state
after the -te form of a verb
Verb て form +
This grammar point is used when an action is performed in advance for future convenience, or to keep/leave something in a specific state for a period of time.
Doing something in advance
This usage indicates that an action is completed now so that it will be useful or necessary at a later time.
パンを買って
I will buy some bread in advance.
地図を調べて
I will check the map beforehand.
Leaving a state as it is
This usage indicates that a certain state is maintained or left as it is for a while.
窓を開けて
Please leave the window open.
テレビをつけて
I will leave the TV on.
Note
In casual speech, ～て