a. responsible
b. responsibility c. responsibly d. irresponsible 8. He has been very interested in doing research on _______ since he was at high school. a. biology b. biological c. biologist d. biologically 9. Although they are twins, they have almost the same appearance but they are seldom in _____. a. agree b. agreeable c. agreement d. Agreeably 10. The more _______ and positive you look, the better you will feel. a. confide b. confident c. confidently d. confidence 11. My parents will have celebrated 30 years of _______ by next week. a. marry b. married c. marriageable d. marriage 12. London is home to people of many _______ cultures. a. diverse b. diversity c. diversify d. diversification 13. Some people are concerned with physical ______ when choosing a wife or husband. a. attractive b. attraction c. attractiveness d. attractively 14. Mrs. Pike was so angry that she made a _______ gesture at the driver. a. rude b. rudeness c. rudely d. rudest 15. She sent me a _______ letter thanking me for my invitation. a. polite b. politely c. politeness d. impoliteness 16. He is unhappy because of his ________________. a. deaf b. deafen c. deafness d. deafened 17. His country has ____________ climate. a. continent b. continental c. continence d. continentally 18. She has a __________ for pink. a. prefer b. preferential c. preferentially d. preference