Study the words in the left column and match them with the meanings in the right column. 1. ______ the study and treatment of diseases and injuries 医学 2. ______ a person who is skilled in sports 运动员 3. ______ relating to space or the universe 宇宙的 4. ______ the part of your leg that bends 膝盖 5. ______ your job or profession 职业 6. ______ the fourth planet from the sun 火星 7. ______ concerning the buying and selling of goods 商业的 8. ______ an advance booking of a seat at a place or event 预约