■若其后直接跟动词要用动名词
He forbids smoking during office hours. 他禁止上班时间抽烟。
The headmaster has forbidden singing in the corridors. 校长禁止在走廊里唱歌。
■若其后先接宾语再跟动词则要用不定式
I forbid him to go there again. 我不准他再去那儿。
The teacher forbids the students to read such books. 老师不准学生看那样的书。
◇比较下面两句
They forbad swimming in the river. 他们不准在这河里游泳。
They forbad people to swim in the river. 他们不准人们在这河里游泳。