instruction: when was the last time that patient 016-35481 was prescribed dextrose and nss infusion at the same time?
response: SELECT t1.drugstarttime FROM (SELECT patient.uniquepid, medication.drugstarttime FROM medication JOIN patient ON medication.patientunitstayid = patient.patientunitstayid WHERE medication.drugname = 'dextrose' AND patient.uniquepid = '016-35481') AS t1 JOIN (SELECT patient.uniquepid, medication.drugstarttime FROM medication JOIN patient ON medication.patientunitstayid = patient.patientunitstayid WHERE medication.drugname = 'nss infusion' AND patient.uniquepid = '016-35481') AS t2 ON t1.uniquepid = t2.uniquepid WHERE DATETIME(t1.drugstarttime) = DATETIME(t2.drugstarttime) ORDER BY t1.drugstarttime DESC LIMIT 1