Final answer:
The correct order of helping verbs concerning the main verb in a sentence with multiple auxiliary verbs is Subject + Second Auxiliary Verb + Main Verb + First Auxiliary Verb. This order is commonly used in English grammar when multiple auxiliary verbs are used to modify the main verb.
Step-by-step explanation:
The correct order of helping verbs concerning the main verb in a sentence with multiple auxiliary verbs is Option d) Subject + Second Auxiliary Verb + Main Verb + First Auxiliary Verb. This order is commonly used in English grammar when multiple auxiliary verbs are used to modify the main verb.
For example, consider the sentence: 'She has been studying hard for her exams.'
In this sentence, 'has been' acts as the first auxiliary verb, 'studying' is the main verb, and 'hard' is the second auxiliary verb.