It is Phong’s sense of responsibility _____ makes him successful in his life.

Knowledge: Split sentence

Explain:

Split sentences are also known as stressed sentences. They are used when you want to emphasize a certain object or event. Sentences are usually divided into two parts, a main part and a relative clause using that, who, when, while…

General structure: It is/was +… that/whom/who +…

Translated: Phong’s sense of responsibility makes him successful in his life.

Answer: EASY