Thefirststepinthestudyofanylanguageisobservingand____preciselywhathappenswhennativespeakersspeakit.
翻译：
Thecaptainrealizedthatthementriedtodeceivehimsohemadethemworkveryhardfortherestofthevoyage.(PassageOne)
Theopeningceremonyisagreatoccasion.Itisessential_____forthat.
John'sscoreonthetestisthehighestintheclass;（）helastnight.