21. All the members .................. to go to the remote areas last year. A. volunteer B. volunteered C. voluntary D. voluntarily 22. The school supports .................. children. A. advantageous B. disadvantageous C. advantaged D. disadvantaged 23. In order to be taken away and used everywhere, modern inventions have a tendency to be smalland................ A. import B. coastal C. airport D. portable 24. More than 40 patterns on silicon surfaces .................. with that paintbrush so far. A. printed B. were printed C. have been printed D. have printed 25. Minerals such as calcium form our teeth and.................. A. bonesB. hands C. heart D. blood 26. Doing volunteering is ...................It makes the world a better place. A. meaningless B. hopeless C. boring D. meaningful 27. I have been given 10 tricks to get rid of my bad habits and ............. them with healthy ones. A. replace B.keep C. nurture D. raise