凍る

1. Origins, structure, and basic meaning

• Structure: 凍る is an intransitive godan verb read こおる, meaning that water or a wet surface becomes frozen.
• Basic usage: Because the thing that freezes is the subject, use が in patterns such as 水が凍る and 道が凍る.
  • 気温が下がると、池の水が凍ることがあります。 says that pond water can freeze when the temperature drops; 濡れた道が凍っていたので、ゆっくり歩きました。 explains walking slowly because the wet road had frozen.

2. Common pitfalls and similar expressions

• 水が凍る
  • が marks the thing whose state changes by freezing; it is not marked as a transitive object's を.
• 凍ることがある
  • ことがある expresses a possibility under certain conditions rather than claiming that freezing always occurs.
• 凍る and 凍らせる
  • 凍る is intransitive and describes something freezing, whereas 凍らせる means causing something to freeze.