Itisnot---_______formetoreturnallthebookstothelibrarynowbecauseIstillneedsomeofthemformyresearch.

Severalloudspeakersare_______fromtheceilingandwecanhearthespeakerveryclearly.

Theengineersinthislabspentseveralweeks_______theirplansforthenewbicycle.

ProfessorSmithisalsothe_______oftheinternationalprogramoffice.Ifyouhaveanyproblemwhenyoustudyhere,youmaygotohimforhelp.

Healwayshasalotof_______ideasinhismind,andsometimeswedonotevenknowwhatheisthindingabout.