Complex object is formed by a noun in the common case or personal pronoun in the objective case + (to) infinitive or participle I (-ing form)

Examples:
1. want, expect etc. + n/pr + to - infinitive: The French king allowed Montgolfier to experiment.
2. see, hear, watch, etc. n/pr + participle I or infinitive without 'to': I saw him (the boy) cross the street. (emphasis on the fact).
3. I saw her (my classmate) crossing the street. (emphasis on the action in progress)
4. let, make + n/pr + infinitive without 'to': The brothers used paper and cloth for the balloon to make it float.