They won't comeunlessyou invite them. The underlined part is an example of -

• They won't come unless you invite them. The underlined part is an example of a subordinating Conjunction.

• There are three basic types of conjunctions:

1. Coordinating conjunctions:
- যা সমমানের দুইটি word, phrase বা clause এর মধ্যে সংযোগ স্থাপন করে।
যেমন: and, or, but, etc…
- I want to go to the beach, and my friend wants to go hiking.

2. Subordinating Conjunctions:
- যে Conjunction একটি clause এর শুরুতে বসে অন্য clause এর স্থান, কাল, ধরণ, মাত্রা, ইত্যাদি বুঝানোর জন্য ব্যবহৃত হয়, তাকে Subordinating Conjunction বলে।
- যেমন: when, as how, if, lest, unless etc…
- They won't come unless you invite them.
- As he is ill, he cannot walk.

3. Correlative Conjunctions:
- পরস্পর সম্পর্কযুক্ত জোড়ায় জোড়ায় ব্যবহৃত conjunction গুলোই Correlative Conjunctions.
- যেমনঃ as ….. as ; either ….. or ; not only ….. but also ; etc.
- Either we go to the movies or we stay at home and watch a movie on Netflix.
- He not only plays the piano but also sings beautifully.