Shebecamea doctor after years of hard work. the underlined part is an example of -

• She became a doctor after years of hard work. Here 'became' is a linking verb.

• Linking verb/ Copulative verb: 
- যে সকল verb সাধারণত subject ও Subjective complement এর মধ্যে যোগসূত্র স্থাপন করে তাদেরকে Linking verb/ Copulative verb বলে।
- Linking verb-এর complement হিসেবে সাধারণত adjective বসে৷
- Subject এবং subjective complement এর মধ্যবর্তী verb কে linking/Copulative verb বলে৷
- অবশ্যই মনে রাখতে হবে - Linking/copulative verb হচ্ছে actionless.
- Turn, be, become, look feel, seem, remain, appear, get, grow etc. সাধারণত Linking verb হিসেবে ব্যবহৃত হয়। কিন্তু এগুলো বাক্যে ব্যবহারে ভিন্নতার কারণে Action verb ও হতে পারে।

• Linking verbs are verbs that don’t show an action but rather describe the subject. While verbs like walk or jump represent an action, linking verbs like be or seem add more details to the subject.

• Linking verbs do not show an action—or more accurately, the only action they show is merely existing. Linking verbs simply explain the state of the subject, such as what it is or how it looks.

• She became a doctor after years of hard work.
- এই বাক্যে subject হলো She, Subjective complement হলো a doctor.
- এর মাঝে রয়েছে Linking verb became.