23. I wondered what difficulty he had _________ the plan?
Wehaveto________thewheatassoonaspossiblebecauseastormisontheway.
Onceadecisionhasbeenmade,allofusshould______it.
Beforethewarbrokeout,manypeople________insafeplacespossessionstheycouldnottakewiththem.
It’stenyearssincethescientist________onhislife’sworkofdiscoveringthevaluablechemical.
Tokeephealthy,ProfessorJohnson_______cyclingasregularformofexerciseafterheretired.