17. Can we have two ... and two ..., please? A coffees, tea B coffee, teas C coffees, teas D a coffee, a tea18. I want a ... of water. A a glass B glass C the glass D glasses19. There are four ... in our class. A Mary's B Mary C Maries D Marys20. Where are the ... magazines? A woman B women's C women D womans's 21. His house is within ... from the central square. A the stone's throw C a stone's throw B stone's throw D a throw of a stone​

17. C. "Can we have two coffees and two teas, please?" is the correct sentence. We use the plural forms "coffees" and "teas" because we are referring to two separate drinks.

18. A. "I want a glass of water" is the correct sentence. We use "a glass" because it refers to one unit of measurement for the water.

19. D. "There are four Marys in our class" is the correct sentence. We use the plural form of "Marys" to indicate that there are multiple individuals named Mary in the class.

20. B. "Where are the women's magazines?" is the correct sentence. We use the possessive form "women's" to indicate that the magazines belong to women.

21. B. "His house is within a stone's throw from the central square" is the correct sentence. The phrase "a stone's throw" is a common idiom meaning a short distance. It does not require an article such as "the" or "a throw of a stone."