Tom has been a vegetarian ____principle for years .
B
【句意】多年来，汤姆一直是一个按原则行事的素食者。
【难点】onprinciple意为“根据行为准则;按照原则”;inprinciple意为“原则上;基本上;大体上”。for和by不与principle搭配。
Thefirststepinthestudyofanylanguageisobservingand____preciselywhathappenswhennativespeakersspeakit.
Thelittleboydidn’tknow_______.
Rumorsareeverywhere,spreadingfear,damagingreputations,andturningcalmsituationsinto____ones.