imouto wa hon o tsukue no ue ni okippanashi ni surukoto ga ooi.

My younger sister often leaves books lying on the desk.

Breakdown of imouto wa hon o tsukue no ue ni okippanashi ni surukoto ga ooi.

• は: topic particle
• 本ほん: book
• を: direct object particle
• の: possessive case particle

Questions & Answers about imouto wa hon o tsukue no ue ni okippanashi ni surukoto ga ooi.

What does 置きっぱなし mean here?

置きっぱなし means left as is after putting something down, often with the nuance that the person didn’t bother to put it away.

It comes from:

• 置く = to place, put
• 〜っぱなし = leaving something in that state; doing something and not following through properly

So 置きっぱなし is not just placed. It implies left there carelessly / left lying around.

In this sentence, it describes books being left on the desk instead of being cleaned up or returned to where they belong.

Why is there a に after 置きっぱなし?

In 置きっぱなしにする, the にする pattern means to make something into that state or to leave something in that state.

So:

• 置きっぱなし = the state of having been left sitting there
• 〜にする = to make/leave it that way

Together:

• 本を置きっぱなしにする = to leave a book lying around / to leave a book where it was placed

This is similar to other patterns like:

• 部屋をきれいにする = make the room clean
• そのままにする = leave it as it is

What does することが多い mean?