Having locked the door, they left for the market. (make it compound)

Simple: Having locked the door, they left for the market.
Compound: They had locked the door and left for the market.

• প্রথমে Subject বসেছে।
- এ বাক্যে Perfect Participle হচ্ছে - Having locked.
- যার past Perfect form হচ্ছে - had locked.
- এরপর গঠন অনুযায়ী বাক্যের বাকী অংশ বসে।

• Perfect Participle যুক্ত Simple Sentence কে Compound Sentence এ পরিবর্তনের নিয়ম:
- প্রথমে Subject বসে,
- Perfect Participle এর past Perfect form বসে,
- and বসে,
- বাকী অংশ বসে।

Simple: Having forgotten him, I went out.
Compound: I had forgotten him and went out.

Simple Sentence: Having prepared the meal, she set the table.
Compound Sentence: She had prepared the meal and set the table.

Source: Advanced Learner's by Chowdhury & Hossain.