Breakdown of keisatsu ga iriguchi o mihatta.
Questions & Answers about keisatsu ga iriguchi o mihatta.
A natural reading is:
けいさつ が いりぐち を みはった。
- 警察 = けいさつ
- 入口 = いりぐち
- 見張った = みはった
So the whole sentence is:
けいさつ が いりぐち を みはった。
が marks the grammatical subject of the sentence: the one who did the action.
So in:
警察 が 入口 を 見張った。
警察 is the one that did the watching/guarding.
If you changed it to は, the sentence would still be possible, but the nuance would change:
警察が入口を見張った。
= It was the police who watched the entrance. / The police watched the entrance.警察は入口を見張った。
= As for the police, they watched the entrance.
This can sound more like a topic, or contrast with something else.
For a simple neutral statement, が is very normal.
