To x For

Preposições são palavras de significado pouco claro e muito variável. São mais partículas funcionais do que palavras de conteúdo semântico definido. A maioria das ocorrências de preposições, não segue um padrão lógico ou regular. Além disso, entre o português e o inglês, as preposições não apresentam uma correlação muito estreita. Cobrem normalmente diferentes áreas de significado, sendo umas de uso mais amplo que outras.
É particularmente notória a dificuldade para nós, brasileiros, quando temos que decidir qual preposição usar em inglês, to ou for, quando em português a idéia seria expressa através da preposição para. Em geral, pode-se dizer que to está ligado à idéia de direção, movimento, correspondendo muitas vezes também à preposição a do português; enquanto que for está relacionado com a idéia de benefício, substituição, intenção ou predestinação, correspondendo, às vezes, ao português por. Esta diferença de significado, entretanto, não é sempre clara. Mesmo assim, for e to raramente podem ser usados como sinônimos.
Freqüentemente to e for introduzem o objeto indireto e é neste caso que as duas preposições normalmente correspondem ao português para. Objeto indireto em inglês é sempre um nome ou pronome que precede ou sucede o objeto direto nos verbos bitransitivos. Quando posicionado antes do objeto direto, não vem acompanhado de preposição. Quando posicionado após o objeto direto, virá invariavelmente acompanhado da preposição to ou for. Neste caso, a preposição certa dependerá do verbo, não havendo regra para isso. Observe os seguintes exemplos:

TO VERBS

FOR VERBS

I gave a present to him. = I gave him a present. I’ll show the figures to you. = I’ll show you the figures. He sold a car to me. = He sold me a car. He sent a letter to Mary. = He sent Mary a letter. Can you lend this book to me? = Can you lend me this book? The boss told a joke to us. = The boss told us a joke. Who teaches English to them? = Who teaches them English? I paid $10 to the repairman. = I paid the repairman $10. Will you pass the sugar to me? = Will you pass me the sugar? Read a story to the children. = Read the children a story. I wrote a letter to my friend. = I wrote my friend a letter. Hand that book to me, please. = Hand me that book, please. He offered a job to Mary. = He offered Mary a job. He'll bring something to me. = He'll bring me something. She sang a lullaby to the baby. = She sang the baby a lullaby. I'll throw the ball to you. = I'll throw you the ball.

Let me buy a present for you. = Let me buy you a present. I got some food for you. = I got you some food. She made a sandwich for me. = She made me a sandwich. Did she cook dinner for you? = Did she cook you dinner? Can you do a favor for me? = Can you do me a favor? He can find a job for you. = He can find you a job. He left a message for you. = He left you a message. Shall I pour more tea for you? = Shall I pour you more tea? Reserve hotel rooms for us. = Reserve us hotel rooms. Save the stamps for him. = Save him the stamps.

Existem também verbos que só aceitam o objeto indireto quando acompanhado de preposição. Exemplos:

TO VERBS

FOR VERBS

The teacher said "Good morning" to the students. He’s going to introduce Mary to his family. I already explained the project to the staff. Mr. Cole described the new house to his wife. I sometimes speak English to (with) my wife. Bob reported the accident to the police. I repeated your ideas to my parents. He admitted his mistake to the boss. I'll mention your plan to the director. Dr. Bishop recommends this medicine to some patients. Richard has announced his engagement to his friends. It sounds good to me. The salesgirl suggested a gift to Philip.

Can you carry the suitcases for me? Could you open the door for me? He asked the bank teller to cash a check for him. Doctors like to prescribe medicine for the patients. She is going to prepare the meal for the guests. I asked her to sign the letter for me. Can you hold this for me, please? I changed the traveler's checks for you. I asked the secretary to make an appointment for me. He translated an article for me. I recorded a tape for you. I'll take the car to the mechanic for you. The salesgirl suggested Philip a gift for his girlfriend. Can you play the piano for me?

Na verdade, quase qualquer verbo aceita o adjunto preposicional for. São portanto ilimitadas as possibilidades de FOR VERBS neste segundo grupo. Observe-se que mesmo os TO VERBS, além de aceitarem o objeto indireto precedido pela preposição to, também aceitam o adjunto preposicional for, porém com outro sentido. Ex:

I sent a letter to Mary.

I sent a letter for Mary.

No primeiro exemplo, Mary mora noutro lugar e eu lhe escrevi mandando notícias. No segundo exemplo, Mary escreveu uma carta para alguém, estava talvez muito ocupada para ir ao correio, e eu fui em lugar dela.
O verbo to go também freqüentemente ocorre associado às preposições to e for. Observe-se os dois grupos abaixo:

GO TO EXPRESSIONS	GO FOR EXPRESSIONS
go to work go to school go to bed go to church go to town go to court go to pieces go to hell go to Porto Alegre go to the bank, go to the office, etc.	go for a walk go for a ride go for a drive go for a beer go for it

Uma das ocorrências mais elementares da preposição to é no uso do infinitivo em inglês. Isto normalmente ocorre na estrutura VERB + to + VERB. Exemplos:

I have to go.
I like to drink beer.
I'm not able to work.
He decided to leave.
You promised to help us.
He's planning to study abroad.
I want to tell you something.
I hope to become fluent in English.
We expect to win the game.

Mesmo quando não introduzem objetos indiretos, a ocorrência das preposições to e for continua dependendo do verbo que acompanham ou da expressão idiomática em que ocorrem. Em muitos casos for corresponde a por do português. Exemplos:

TO EXPRESSIONS

FOR EXPRESSIONS

Nice to meet you. Up to date To my surprise, ... To the best of my knowledge, ... According to ... Apply to a university. He reacted well to my comments. I object to staying up late. I'm accustomed to working hard. I'm not used to working on Sundays. It's very sensitive to cold weather. To (for) me, it sounds good. It's interesting to me. She was invited to a party. I'm looking forward to hearing from you. It's a hundred miles from here to Porto Alegre. They raised his salary to $1,000. Don't jump to conclusions.

For sure! For God's sake! Good for you! For example, ... For this reason ... For the first time ... For (to) me, it sounds good. Apply for a job. Any letters for me? I feel sorry for them. He left for home. I have a question for you. He works for a tobacco company. I sold my house for 40 thousand dollars. He charged 50 dollars for the translation. I lived abroad for 7 years. He's very strong for an old man. I'm looking for a job. He received a grant for studying medicine. I want eggs for breakfast. I wrote a check for $100.