If the weather had been nice yesterday, we ______ to the zoo.
Explanation
If the weather had been nice yesterday, we would have gone to the zoo.اگر کل موسم اچھا ہوتا تو ہم چڑیا گھر میں جاتے۔ This is a third conditional sentence, which refers to an unreal past condition and its hypothetical result.The correct structure is "would have + past participle", so "would have gone" is grammatically correct.