A. before B. air-resistance C. pleasant D. moo A. single B. difficult C. casual D. society A. volleyball B. overfish C. tram D. goodbye A. requisite B. jogging C. wear D. sticker A. vibration B. fan C. grasp D. writing paper A. association B. attainment C. ask D. boo A. racial B. any C. Yes,please D. carelessly A. quagga B. ecosystem C. flap D. party A. educated B. angry C. grapefruit D. end up A. stick to B. approach C. heavy D. green with envy