Question

why can the to be dropped?He helped to write the program.

Accepted Answer

When the infinitive follows some verbs (helped here) as the direct object, the to may be dropped.He helped write the program.

Front	why can the to be dropped? He helped to write the program.
Back	When the infinitive follows some verbs (helped here) as the direct object, the to may be dropped. He helped write the program.

Helped Write Program Be Dropped Infinitive Verbs Direct