They smiled at one another, knowing they had accomplished something great. Here 'one another' is -

• They smiled at one another, knowing they had accomplished something great. Here 'one another' is - Reciprocal pronoun.

• Reciprocal pronoun:
- এই pronoun একাধিক ব্যক্তি বা বস্তুর মধ্যে পারস্পরিক সম্পর্ক বুঝায়।
- পারস্পরিক সম্পর্কের ক্ষেত্রে each other এবং one another এই দুইটি pronoun ব্যবহার করা হয়, যারা reciprocal pronoun নামে পরিচিত।
- One another, Each other হচ্ছে Reciprocal pronoun.

Example Sentence:
1. The team members supported one another during the challenging project.
2. The two friends forgave each other for the misunderstanding.

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• Pronoun ৮ প্রকার। যেমন:
1. Personal pronoun: (I, we, me, it)
2. Demonstrative pronoun: (this, that)
3. Interrogative pronoun: (what, who)
4. Relative pronoun: (what, who, that)
5. Indefinite pronoun: (one, some, any, all, many)
6. Distributive pronoun: (each, every)
7. Reflexive pronoun: (myself, themself)
8. Reciprocal pronoun: (each other, one another)

Source: Advanced Learner's Grammar and Composition by Chowdhury and Hossain.

Source: Applied English Grammar and Composition by P C Das.