Student 1: -1-

Student 2: -1-

Student 3: -0-

A modifier describes, clarifies, or gives more detail about a concept. 

• A dangling modifier is a word or phrase that modifies a word not clearly stated in the sentence.
  • Dangling modifier: Student 1 — Having arrived late for practice, a written excuse was needed.
    Who arrived late? This sentence says that the written excuse arrived late. To revise, decide who actually arrived late.
    Example: Having arrived late for practice, Rahul Doer needed a written excused.
  • Dangling modifier: Student 2- Without knowing his name, it was difficult to introduce him. 
  • Who didn't know his name? 
    This sentence says that “it” didn't know his name. To revise, decide who was trying to introduce him.
    Example: Since Jayanti doer didn’t know his name, it was difficult to introduce him.
  • Student 3: The experiment was a failure, not having studied the lab manual carefully. This sentence is not an example of dangling modifiers.

Hence, student 1 and student 2 provide correct examples of dangling modifiers used in these sentences. Thus, the score for both of them is 1 and for student 3 is 0.