1) De manhã/de tarde/de noite= in the morning/in the afternoon/at night. You just know that. Ex1) Eu gosto mais de ter aulas de tarde do que de manhã. => I like to take classes in the afternoon rather than morning. 2) Pela manhã/pela tarde/pela noite = in the morning/in the afternoon/by night. It yields the image that you, most probably (may be not) , could have done (or will do) it intermittently or throughout all time. Ex2) Eu gosto muito de ir à praia e tomar o sol pela manhã. => I really like going to the beach and sunbathing in the morning. 3) À tarde/à noite=in the afternnon/ in the evening (at night, tonight). It yields the image that you, most probably (may be not), are "waiting" fot that time to arrive and that you are not inside that time yet. "À manhã" does not exist because it developed to "amanhã"=tomorrow Ex3) "À noite, vou acabar de ler este livro." => At night, I will finish reading this book. 4) Da manhã/da tarde/da noite=belonging to the morning time/afternnon time/(evening+night) time. Ex4) Neste momento, são 5 horas da manhã. => At this point, it's 5 o'clock in the morning. 5) Na manhã/na tarde/na noite=inside the morning time/afternnon time/(evening+night) time of a certain day... Ex5) O crime deu-se na manhã do dia 5. => The crime occurred on the morning of the 5th.

Here are some examples, hope it helps Eu estudo de manhã - I study in the morning De manhã eu não consigo estudar direito - In the morning I can't study well A luz da manhã - morning light (The light of the morning) São 4 (horas) da manhã - It's 4 in the morning Eu te procurei pela manhã (inteira) - I looked for you all morning (It implies that it happened throughout the morning) Vamos dirigir pela noite - We will drive throughout the night; which is slightly different from we will drive at night, but doesn't make a huge difference.

This is hard! Prepositions!!! I hate them, even in English hahahh sorry! Let's try: Da manhã = belongs to the morning period (pertence ao período da manhã), I think we just use this term when we are talking about the breakfast (café da manhã). also you can use with hours, period of that specif time like: são 8 horas da manhã "it's 8 o'clock am". De manhã = something that you or somebody do at morning period, I was at his house at the morning (eu estava na casa dele de manhã. Don't worry about it

Using standard translate all that meanins " In the morning" But using the Portuguese thinking, " Pela Manhã" also "De Manhã" mean something that happens or we do during the morning period. "Da Manhã" means something belongs to the morning period.

O carteiro, de manhã, não veio. [de manhã expressa quando o carteiro não veio] O carteiro da manhã não veio. [da manhã expressa que há mais de um carteiro (um que vem de manhã e outro à tarde, por exemplo), ou seja, qual dos carteiros não veio] o mesmo pode ser para a NOITE e Tarde