It appears to this pedantic ass, that you are confusing the verbs "to lie" and "to lay." The former describes how something is situated, and is intransitive, that is, does not take a direct object, while the latter refers to putting something down, as a chicken lays an egg, and is a transitive verb that requires a direct object. Your non-standard usage is probably the most common error to be found in English. Proper usage would be "...the object is lying in a horizontal position." Incidentally, the indefinite article "a" is preferred to "an" when preceding a word beginning with a consonant sound.
Now I remember! Спасибо!
Off topic: For french speakers. My girlfriend told a french person "Où est le paquet!" for "Where can I get a plastic bag". If you ever say that, it looks like you're asking for THE PACKAGE ("Where is the package?"), like you are doing a secret exchange of illegal objects haha!
IMHO «мусорный мешок» ~ «мешок для мусора» can be used for a garbage bag too.
Russian nouns have several forms called cases.
Сумка is the nominative case, used when сумка is the subject (Сумка упала 'The bag felt'), or in 'X is Y' sentences (Это сумка 'this is a bag').
Сумке is a prepositional case, used with some prepositions to indicate location.
I know it’s late to answer, but no. We say «в карма́не» ‘in the pocket’ instead.
'Present' is the subject here.
In general, Russian places known information in the beginning of the sentence, and new information in the end. So, you can change the word order depending on what you want to say:
- Мой подарок лежит в сумке. 'My present is in the/a bag.' This is a sentence about 'my present'. I tell a new information about 'my present': the fact that it's in the bag.
- В сумке лежит мой подарок. 'In the bag, there is my present.' This is a sentence about 'the bag'. It tells new information about the bag: the fact that my present is there.
- Мой подарок в сумке лежит. 'My present is [indeed] in the/bag.' This word order emphasises лежит, either to show that the present is indeed laying, is indeed placed horizontally, and not vertically, or to emphasise the fact that the present is actually there.