Question 7: As soon as the boys ___________ the hall they ___________t

Question 7: As soon as the boys ___________ the hall they ___________to speak about books and writers.

• A. entered/begun
• B. were entering/began
• C. entered/began
• D. had entered/began

As soon as + S + V(quá khứ đơn), S + V(quá khứ đơn) => diễn tả hành động xảy ra nối tiếp nhau trong quá khứ