A. professional B. go to a summer camp C. rapids D. slip A. invest B. pay for C. ceiling D. substitute A. tetrahedron B. hybrid C. adverse D. long-eared A. seat B. cheetah C. unutterable D. penguin A. propulsion B. broom C. pleasure D. anything A. up-to-date B. clue C. P.M. D. radiance A. acre B. ought to C. vulgar D. head teacher A. lastly B. albatross C. hub D. cab A. sustenance B. potato chips C. sunrise D. frequently A. due B. mail C. vary D. omen