The teacher saw the students 【playing】 on the playground at 5 pm yesterday.
see sb do sth 省略to的不定式,即動(dòng)詞原形做賓補(bǔ),強(qiáng)調(diào)【動(dòng)作全過(guò)程】
see sb doing sth v-ing做賓補(bǔ),強(qiáng)調(diào)【動(dòng)作正在進(jìn)行】
see sb/sth done 過(guò)去分詞做賓補(bǔ),強(qiáng)調(diào)【賓語(yǔ)與該動(dòng)作是被動(dòng)關(guān)系】
這里,突出動(dòng)作正在進(jìn)行,因此用playing.再如：
The managers would like to 【see the plan carried out】when they come back.
The lost boy were last seen playing on the beach.
The witness 【 saw the defendant come over and enter】 that house through the window.
祝你開心如意!