Choose the underlined part that needs correcting in each sentence below.
17. Hoa is sitting among Lan and Cuong at the moment.
A. is sitting B. among C. and D. at the moment
18. There are an atlas, a book, a notebook, a computer and a pen on the table.
A. are B. an C. and D. on the table
19. What is the long of the Nile River?
A. What B. long C. of D. Nile River
20. We are understanding our today’s lesson now.
A. are understanding B. our C. today’s D. now
21. He often asks me many difficult questions, so I can’t answer it.
A. asks B. difficult C. so D. it
17b. among -> between
18 a. are -> is
19. b.long -> length
20. a. are standing -> understand
21. d. it -> them