They (leave) the house before the rain started.

• শূন্যস্থানে সঠিক উত্তর হবে - had left.
- Complete sentence: They had left the house before the rain started.

• Before যুক্ত বাক্যের গঠন-
- Sub + past perfect + before + past indefinite.
-যেমন - She had already completed her work before the meeting started.
- (এখানে before-এর আগে past perfect tense এবং এর পরে past indefinite বসেছে)।

• অন্যদিকে,
• After যুক্ত বাক্যের গঠন-
- Sub + past indefinite + after + sub + past perfect tense + object.
- The team celebrated after they had won the championship.
- এখানে after -এর পর past perfect tense এবং এর আগে past indefinite বসেছে)
-যেমন - The children played outside after they had completed their homework.