Every means ____ tried out but never with success, as far as my knowledge goes.
A、isC
【句意】就我所知，每種方法都試過了，但都沒有成功。
【難點】means雖以s結尾卻是單數形式，因此謂語動詞應選用第三人稱單數。
Tom,withhisparents______toAmerica.They_____backintwoweeks.
______theyaretwinsisters,theydon’tlooklikeeachother.
The____populatedareawasabreedingplaceforinfectiousdiseases.
WeexpectMr.Whitewill____ClassOnewhenMissJaneretires.
It’snecessary______ustokeepourpetscleaneveryday.
