16. We have the custom of ………Sunday together. a. spend b. to spend c. spending d. spends 17. Nick likes………Vietnamese. a. to learn b. learning c. learns d. learn 18. According to tradition, you………clean the floor on the first day of Tet. a. should b. have to c. shouldn’t d. don’t 19. In Russia, you………stand in the doorstep because it can bring bad luck. a. should b. don’t have to c. have to d. shouldn’t 20. I will take………umbrella in case it rains. a. a b. an c. the 21. ………Thai’s main food is rice, especially sticky rice. a. A b. An c. The 22. It’s the custom in that country for women ………married in white. a. to get b. get c. gets d. getting