----- Nội dung dịch tự động từ ảnh ----- The relationship between teachers and students is less formal in the US (16)_ in many other countries, especially at college level. American college students do not stand up (17) their teachers enter or leave the classroom. Students are generally encouraged to give extra help, and even to phone (18) during class, to stop by professors' offices (19). if they are absent. Most teachers allow students to enter the class late or leave (20) 16. a. as b. so d. more c. than c. if 17. a. when b. which d. because 18. a. money 19. a. by 20. a. on time b. decision b. on b. early c. out c. for c. late d. questions d. about d.allare correct