What is/are the direct object(s) in the following sentence?: The werewolf is scaring the other monsters.
The direct object of this sentence is 'the other monsters'.
One of the ways to find a direct object of a sentence is to change it to Passive Voice. If such change is possible, then the subject of the Passive Voice sentence is the direct object of the original sentence.
The sentence is 'The werewolf is scaring the other monsters.'.
If we change it to Passive we get:
The other monsters are being scared by the werwolf.
The phrase 'the other monsters' became the subject in Passive Voice, so it is a direct object in the original sentence.
On the other hand if we try the same algorithm with the sentence
"Jack danced with Alice all night." it will not give any result. There is no word which could become the subject in Passive Voice sentence, therefore the original sentence does not have a direct object.