Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct word or phrase that best fits blank (21). In the United States and Canada, it is very important to (17) ______a person directly in the eyes when you are having a conversation with him or her. If you lookdown or to the side when the (18) ______ person is talking, that person will think that you are not interested in what he or she is saying. This, of course, is not polite. If you look down or to the side when you are talking, it might (19) ______ that you are not honest. However, people who are speakingwill sometimes look away for (20) ______ seconds when they are thinking or trying to find the right word. But they always turn immediately back to look the listener directly in the eyes. These social "rules" are (21) ______for two men, two women, a man and a woman, or an adult and a child. A: likely B: like C: the same D: such as (chỗ số 21)