6、室。句子中如有yesterday,last,justnow,in1999等过去时间词就只用一般过去时。特别提醒:句子中如有特殊疑问词when出现,一定不能用完成时。( B )①—ThesefarmershavebeentotheUnitedStates.—Really?When________there?A.willtheygo B.didtheygo C.dotheygo D.havetheygo( B )②—________you________yourhomeworkyet?—Yes,I________itamomentago.A.Did;do;finishedB.Have;done