" ___なければ___" 

The Japanese grammar pattern "なければ" is used to express a conditional relationship where the first clause sets a condition that, if not met, affects the outcome or action in the second clause.

This structure is often translated to "if not" or "unless" in English.

To form this pattern, you take the negative form of an adjective or verb, drop the "い" at the end, and add "ければ."

For example, the adjective 高い (takai, meaning "expensive") becomes 高くない (takakunai, meaning "not expensive"), and then 高くなければ (takakunakereba, meaning "if not expensive").

Similarly, the verb 合う (au, meaning "to fit") becomes 合わない (awanai, meaning "does not fit"), and then 合わなければ (awanakereba, meaning "if it does not fit").

Examples:

あの　家　を　高くなければ　買いたい。

If that house is not expensive (I) like to buy.

この　くつ　を　あなた　に　合わなければ　買わなくて　いいよ。

If these shoes do not fit you, it is ok not to buy (them).