5. The correct answer is D. "grown" should be changed to "is grown" to make the sentence grammatically correct: "Viet Nam exports a lot of rice which is grown mainly in the south of the country."

6. The correct answer is D. "die" should be changed to "the" to make the sentence grammatically correct: "Although her awful pain, she tried to walk to the classroom to attend the lecture."

7. The correct answer is D. "that" should be changed to "they" to make the sentence grammatically correct: "Those students are trying their best in order that they get the scholarship."

8. The correct answer is A. "school" should be changed to "schools" to make the sentence grammatically correct: "More schools are using modern technology in teaching and learning English."