Wemust______thattheexperimentiscontrolledasrigidlyaspossible.
Aftersomanydayswithoutrain,thegroundquickly________thelittlerainthatfelllastnight.
Iboughtthiseighteenthcenturywritingdeskataquite________price.
SinceWilliamhadbeenseriouslyillforseveralmonths,hisparentswereworriedabout________toreturntoschoolfull-time.