There are certain words that tend to trip up some test-takers. Here are the practical issues that surround the most common culprits:
Some: This word literally means "at least one." If you read sentences so that you hear "at least one," you'll have an easier time following arguments. For example:
Or: To a logician, there are two kinds of "or": inclusive and exclusive. An exclusive or means A or B but not both. An inclusive or means A or B or both. On the GMAT, or is always inclusive. For example:
Phenomenon: The word phenomenon (plural: phenomena) often gives test-takers pause. It simply means "thing." All you have to do is substitute "thing" for "phenomenon" in any sentence and you have not altered the meaning at all. For example
Some oak trees in the forest are taller than the tallest maple trees.
At least one oak tree in the forest is taller than the tallest maple tree.
"Steve is taking Katie or Kara along to the library" means that Steve is taking either Katie or Kara, or both, to the library.
On the GMAT, an exclusive or will have the words "but not both" added. This is actually quite rare.
Researchers have observed many unusual phenomena at the crash site.
Researchers have seen many unusual things at the crash site.
Note that we also paraphrased "observed" to "seen." It is a good idea to simplify the language of the arguments and question stems as much as you can without changing the meaning or structure.