Câu 1:"doing exercise"

Câu 2: "what"

Câu 3:  My students are not so good at Mathematics, but they study English well. (instead of "good")

Câu 5:  I was delighted to see all of my old friends again in a new place last week. (instead of "seeing")

Câu 6:  It took me an exceptionally long time to recover from the shock of her death. (instead of "recovering")

Câu 7:  Thomas’s parents are very sad to see that he doesn't usually do his homework. (instead of "sadly")

Câu 8:  Jamie was the last person to get on the bus after the trip to Ong Temple. (instead of "getting")

Câu 9:  Having failed 2 classes at the same time was an unforgettable memory. (instead of "were")

Câu 10:  Having qualifications from good educational institutions helps young people find jobs easily after graduation. (instead of "educator" and "find jobs easily")

Câu 11:  Having studied for 12 years, I can finally take some rest after the national entrance exam. (instead of "been studied")

Câu 12:  Hellen is the first girl to propose the idea of restoring the old temple. (instead of "proposes")

Câu 13:  You can earn an academic degree at higher education institutions. (instead of "academy" and "institutions")