Students shouldn’t be given so difficult a problem ______they can not work out.
Nobodynoticedthethiefslipintothehousebecausethelightshappenedto_______.
TheInternethasbrought_______bigchangesinthewaywework.
Idon’t______rock’n’roll.It’smuchtoonoisyformytaste.
Itwasnotaseriousillness,andshesoon_______it.
Theforestguardsoftenfindcampfiresthathavenotbeen________completely.