Unit two, astronaut. astronaut. gravity. gravity. absence. absence. float. float. cupboard. cupboard. ceiling. ceiling. bother. bother. occupy. occupy. mission. mission. evaluate. evaluate . creature. creature. mosquito, mosquitoes. es, mosques, mosque, es. microscope. microscope. cast new light on. cast new light on . maintenance. maintenance. Circumstances. the circumstances in . the circumstances. exposure. exposure. radiation. radiation. visible. visible. in view of. in view of . luxury. luxury. tube. tube. Furthermore. furthermore. pill. pill. vital. vital. discipline. discipline. leisure. leisure. crew. crew. permanent. permanent. altogether. altogether. Kit. kit. telescope. tell a scope. universe. universe. crucial. crucial . orbit orbit astronomer. astronomer. merely . merely . administration. administration. agency. agency. comprise . comprise . scan. scan. plan to see. plan to see . foundation. foundation. lay the foundation for. lay the foundation for purse, purse. tail. tail. origin. origin. shuttle. shuttle frequency, frequency, hydroid gen. hydrogen en rocket. rocket . motive. motive. investment. investment. calculate. calculate . coverage. coverage. mechanic. mechanic. assistant. assistant. incredibly. incredibly. dust. dust. shelter. shelter. constant. constant. nuclear. nuclear.