dont put a period
In this kind of sentence, "how" is usually considered an adverb, modifying the verb infinitive "to write".
This probably refers to the absence or presence of the infinitive marker "to." In the sentence "I must go" the infinitive ( "go") lacks the marker, while in the sentence "I want to go" the infinitive has it.
The infinitive phrase plays the role of an adverb in this sentence. It tells why you met at the park. In the sentence "You met at the park to run", "to run" is the infinitive phrase.
Yes, a sentence can end with an infinitive. For example, "I asked him to help."
infinitive
The infinitive in this sentence is "to keep." It is the base form of the verb "keep."
In the sentence I want to open the can, can is the object of the verb "to open."The verb is "want." "To open the can" is an infinitive phrase, serving as the direct object of "want." The infinitive itself is "to open." "Can" is the object of the infinitive.
Write into as one word. It is one preposition and should be treated as such. If perhaps in some strange sentence, the word to was part of an infinitive, then the in and the to would be separate. Maybe someone could figure out such a sentence but it would be difficult.
"to finish your test" is the infinitive phrase.
finish the complete infinitive phrase is "to finish mowing the yard".
The infinitive phrase is "to join the circus" (an adverbial phrase).
noun, adjective, and adverb