They have been studying for the exam all night. Here 'have been studying' is a/an -

•They have been studying for the exam all night. Here 'have been studying' is a - Verb phrase.
• Verb Phrase:
- যে phrase - verb এর কাজ করে সেটি Verb Phrase.
-A verb phrase consists of a main verb alone, or a main verb plus any modal and/or auxiliary verbs.
- The main verb always comes last in the verb phrase

• অন্যদিকে,
• Phrasal Verb:
- বাক্যে Verb + preposition/adverb থাকলে সেটা Phrasal Verb হয়।
- যেমন - look down upon, give up, look after.
- তাই এখানে Phrasal Verb (verb + preposition) হচ্ছে phrasal verb.