I have a last doubt.
Thank you
I taught to my students (or my students?) how to speak?
I'll write to you soon.
I can't understand why in English the indirect object is not always preceded by "to". Can you give me examples? Thank you.
He gave his life to his fatherland. Or He fell for his homeland.
I taught my students how to speak.
By definition, an indirect object is not preceded by "to." Indirect objects always come between the verb and the direct object, and often follow these verbs: give, bring, teach. This site has more examples.
http://www.slu.edu/colleges/AS/languages/classical/latin/tchmat/grammar/g-indob.html
Indirect objects:
I gave him a cup of coffee.
I taught my students.
The waitress brought us or salads.
If you have studied Latin, you'll find the same thing. Indirect objects are in the dative case and have no preposition.
Latin prepositions are used either with the accusative or the ablative case, depending on the meaning. (Usually any preposition implying movement toward something is followed by a noun or pronoun in the accusative case.)
In English, the indirect object is not always preceded by "to" because it depends on the specific verb that is being used. Some verbs require the use of "to" before the indirect object, while others do not.
For example, in the sentence "I taught my students how to speak," "my students" is the indirect object and does not require the use of "to" before it. The verb "taught" does not require the use of "to" in this context.
On the other hand, in the sentence "He gave his life to his fatherland," "his fatherland" is the indirect object and it is preceded by "to." The verb "gave" requires the use of "to" before the indirect object in this context.
In your second example, the sentence "He fell for his homeland," the phrase "for his homeland" is not functioning as an indirect object. Here, "for" is used to express falling in love or developing strong feelings towards something, and "his homeland" is the object of the preposition "for."
So, whether or not "to" is used before an indirect object in English depends on the specific verb being used. It is important to learn the correct usage of each verb and whether it requires "to" or not.