Explanations:The present perfect tense is used to describe actions that occurred at an unspecified time before now and have a connection to the present. It is formed with the auxiliary verb "have" or "has" followed by the past participle of the main verb. The choice of "have" or "has" depends on the subject of the sentence. For plural subjects, "have" is used, while for singular subjects, "has" is used.
In the given sentence, "The singers ..... on stage for many songs," the subject "singers" is plural. Therefore, the correct auxiliary verb to use is "have." The past participle of the verb "sing" is "sung." Thus, the correct form is "have sung."
Let's examine why the other options are incorrect:
Option B, "doesn't sing," is in the simple present tense and does not fit the context of an action that occurred in the past. The simple present tense is used to describe habitual actions or general truths, not actions that occurred at an unspecified time before now.
Option C, "didn't sung," is grammatically incorrect. The correct past form of "sing" is "sang," and "didn't" should be followed by the base form of the verb. Therefore, the correct form would be "didn't sing," but this is in the simple past tense, which does not convey the present relevance implied by the present perfect tense.
Option D, "sang," is in the simple past tense, which describes a completed action in the past. It does not convey the present relevance implied by the present perfect tense. The simple past tense is used to describe actions that occurred at a specific time in the past, not actions that occurred at an unspecified time before now.
Option E, "has been singing," is in the present perfect continuous tense, which implies an ongoing action that started in the past and continues to the present. The context of the sentence does not suggest ongoing action, so this form is not appropriate.
Therefore, the correct answer is "have sung," which correctly uses the present perfect tense to describe actions that occurred at an unspecified time before now and have a connection to the present.