1. clothes, cloth, clothing
clothes統指各種衣服，謂語動詞永遠是複數， cloth指布，為不可數名詞 clothing 服裝的總稱，指一件衣服用a piece of, an article of
2. incident, accident
incident指小事件, accident指不幸的事故he was killed in the accident.
3. amount, number
amount後接不可數名詞， number後接可數名詞 a number of students
4. family, house, home
home 家，包括住處和家人，house房子，住宅，family家庭成員. my family is a happy one.
5. sound, voice, noise
sound自然界各種各樣的聲音，voice人的嗓音，noise噪音i hate the loud noise outside.
6. photo, picture, drawing
photo用照相機拍攝的照片，picture可指相片，圖片，電影片，drawing畫的畫 let's go and see a good picture.
7. vocabulary, word
vocabulary辭彙，一個人擁有的單詞量，word具體的單詞he has a large vocabulary.
8. population, people
population人口，人數，people具體的人 china has a large population.
9. weather, climate
weather一天內具體的天氣狀況，climate長期的氣候狀況 the climate here is not good for you.
10. road, street, path, way
road具體的公路，馬路，street街道，path小路，小徑，way道路，途徑 take this road; in the street, show me the way to the museum.
11. course, subject
course課程（可包括多門科目），subject科目（具體的學科）a summer course
12. custom, habit
custom傳統風俗，習俗，也可指生活習慣，後接to do， habit生活習慣，習慣成自然，後接of doing. i've got the habit of drinking a lot. (過去進行)have+past participle
13. cause, reason
cause 指造成某一事實或現象的直接原因，後接of sth./doing sth，reason用來解釋某種現象或結果的理由，後接for sth./doing sth. the reason for being late
14. exercise, exercises, practice
exercise運動，鍛鍊（不可數），exercises練習（可數），practice（反覆做的）練習 practice makes perfect.
15. class, lesson
作"課"解時,兩者可以替換.指課文用lesson. 指班級或全體學生用class. lesson 6; class 5