Final answer:
The sentences in the passage use different tenses such as the simple present, simple past, and present perfect. Each tense is applied depending on the context and the time that the action is referring to.
Step-by-step explanation:
The passage applies different verb forms and tenses in different contexts. In the sentence, 'The Great Pacific Garbage patch is (simple present form of 'be') a mass of plastic debris,' it uses simple present tense. The second sentence, 'It was discovered (simple past form of 'discover') by Charles Moore in 1997,' uses simple past tense. In 'He has been (present perfect form of 'be') a sailor participating in a yacht race,' the present perfect tense is used. Then, we see the simple past in 'He took (simple past form of 'take') a shortcut and came (simple past form of 'come') across floating pieces of garbage.' And again, the simple past tense is applied in 'The sight changed (simple past form of 'change') him forever.' Finally, the sentence 'Now he works (simple present form of 'work') to raise awareness about it' utilizes the simple present tense.
Learn more about Verb tenses