1. rational, reasonable
rational a. 理性的，區別於無理性；理智的，區別於感情用事的。
The rational thing to do was to take the sick man to a doctor.
理智的做法是送病人去看醫生。
reasonable a. 有道理的`，公平合理的，或指人講道理的。
That man works very hard, so it is reasonable for him to ask for more money.
那個人工作努力，所以他要求加薪是合情合理的。
2. refrain, restrain, constrain
refrain v. 抑制，禁止，強調抑制一種衝動，是正式用語，爲不及物動詞，後接介詞from。
Students refrain from smoking in the classroom.
學生們剋制住不在教室抽菸。
restrain v. 抑制，約束，指通過管束阻止某事發生，是及物動詞，其習慣用法是restrain sb. (sth.) from doing。
She restrains her dog by walking him on a leash.
溜狗時，她牽着狗來限制它的活動。
constrain v. 強迫，力勸，是及物動詞。
A law constrains the government from spending more money than it takes in.
法律限制政府開支大於收入。
3. respectable, respectful, respective一組形近易混詞。
respectable a. 值得尊敬的，有好名聲的。
They are respectable people who are liked and trusted in their town.
他們在家鄉是受人們敬愛和信任的人。
respectful a. 尊敬他人的，恭敬的。
Students and teachers should have a respectful attitude toward each other.
師生應該相互彬彬有禮。
respective a.單個的，分別的。
4. revolve, evolve, involve
revolve v. 旋轉，轉動。
The room began to revolve , then he fainted.
屋子開始旋轉，然後他就昏倒了。
evolve v. 發展，演變。
Agriculture evolved slowly over thousands of years.
幾千年來，農業發展得很緩慢。
involve v. 需要，包含；使捲入，牽涉。
Getting a driver's license involves learning how to drive, studying the rules of the road, and taking a test.
要得到駕駛執照需要學習開車，學習交通規則，還要經過考試。
5. sanction, sanitation
sanction" class="hjdict" word="sanction" target=_blank>sanction n. 認可，准許，批准。
I need my parents' sanction to stay out late.
我晚回家需要得到父母的批准。
sanitation" class="hjdict" word="sanitation" target=_blank>sanitation n. 公共衛生，環境衛生，衛生設備。
Strict sanitation is used in businesses such as barber shops and restaurants.
在理髮店和餐館等營業場所執行嚴格的公共衛生制度。
