Grammar for Everyone - Barbara Dykes 2007

Adverbial clause of purpose
Introduction
Part II The parts of speech

This clause tells us why something is done.

Finite verbs:  is working, can become

Main clause:  she is working hard

Conjunction:  so that

Subordinate clause: she can become an entomologist

Adverbial clause of purpose, modifying the verb ’is working’ in the main clause

Complex sentence