10.NosoonerhadMrs.Foxfinishedexplainingthepoemthanthestudents’questions_________topourin.[A]begin[B]beginning[C]began[D]hadbegan11.Theexperiments_________inboththeUnitedStatesandEuropewellbefore1900.

　　10.NosoonerhadMrs.Foxfinishedexplainingthepoemthanthestudents’questions_________topourin.

　　[A]begin[B]beginning[C]began[D]hadbegan

　　11.Theexperiments_________inboththeUnitedStatesandEuropewellbefore1900.

　　[A]havebeenconducting[B]wereconducting

　　[C]hadbeenconducted[D]haveconducted

　　19.WhenIgotbackhomeIsawamessagepinnedtothedoor____“Sorrytomissyou;willcalllater.”

　　[A]read[B]reads[C]toread[D]reading

　　20.Itwasnotuntilhefinishallhishomework___________tobedlastnight.[A]didhego[B]whenhewent[C]thathewent[D]thenhewent