ame de keikaku ga dainashi ni natta.

subject particle

Breakdown of ame de keikaku ga dainashi ni natta.

• 雨あめ: rain
• なる: to become
• に: target particle

Questions & Answers about ame de keikaku ga dainashi ni natta.

Why is 雨 followed by で here?

Here, で marks the cause/reason: because of the rain.

This is a common use of で with things like:

• weather
• accidents
• illness
• natural causes

So 雨で means due to the rain or because of the rain.

It is not the location use of で in this sentence.

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Why is 計画 marked with が instead of を?

Because 計画 is the thing that became ruined, so it is the grammatical subject of 台無しになった.

The pattern is:

• X が Y になった = X became Y

So:

• 計画が台無しになった = the plan became ruined

If you used を, you would normally need a transitive verb, such as:

• 雨が計画を台無しにした = the rain ruined the plan

In your sentence, the structure is intransitive: the plan became ruined.

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What exactly is 台無し?