Articles, that/this & those/these, preposition.
The first most-likely grammatical error is definite articles. Here are the rules to use articles:
Basically, an article is an adjective. Like adjectives,articles modify nouns.
The definite article is used before singular and plural nouns when the noun is specific or particular. The signals that the noun is definite, that it refers to a particular member of a group.
The can be used with noncount nouns, or the article can be omitted entirely. There are some specific rules for using the with geographical nouns.
Geographical use of The
Do not use the before:
- names of most countries/territories: Italy, Mexico, Bolivia; however, the Netherlands, the Dominican Republic, the Philippines, the United States
- names of cities, towns, or states: Seoul, Manitoba, Miami
- names of streets: Washington Blvd., Main St.
- names of lakes and bays: Lake Titicaca, Lake Erie except with a group of lakes like the Great Lakes
- names of mountains: Mount Everest, Mount Fuji except with ranges of mountains like the Andes or the Rockies or unusual names like the Matterhorn
- names of continents (Asia, Europe)
- names of islands (Easter Island, Maui, Key West) except with island chains like the Aleutians, the Hebrides, or the Canary Islands
Do use the before:
- names of rivers, oceans and seas: the Nile, the Pacific
- points on the globe: the Equator, the North Pole
- geographical areas: the Middle East, the West
- deserts, forests, gulfs, and peninsulas: the Sahara, the Persian Gulf, the Black Forest, the Iberian Peninsula
The other common mistakes is the misuse of reciprocal pronouns.
The reciprocal pronouns are each other and one another. They are convenient forms for combining ideas. If Bob gave Alicia a book for Christmas and Alicia gave Bob a book for Christmas, we can say that they gave each other books (or that they gave books to each other).
- My mother and I give each other a hard time.
If more than two people are involved (let's say a whole book club), we would say that they gave one another books. This rule (if it is one) should be applied circumspectly. It's quite possible for the exchange of books within this book club, for example, to be between individuals, making "each other" just as appropriate as "one another."
Reciprocal pronouns can also take possessive forms:
- They borrowed each other's ideas.
- The scientists in this lab often use one another's equipment.