Schistosomiasis, a disease caused by a parasitic worm, is prevalent in hot, humi

游客2024-01-12  21

问题 Schistosomiasis, a disease caused by a parasitic worm, is prevalent in hot, humid climates, and it has become more widespread as irrigation projects have enlarged the habitat of the freshwater snails that are the parasite’s hosts for part of its life cycle.

选项 A、the freshwater snails that are the parasite’s hosts for part of its life cycle
B、the freshwater snails that are the parasite’s hosts in part of their life cycle
C、freshwater snails which become the parasite’s hosts for part of its life cycles
D、freshwater snails which become the hosts of the parasite during the parasite’s life cycles
E、parasite’s hosts, freshwater snails which become their hosts during their life cycles

答案 A

解析 Rhetorical construction; Agreement
This sentence explains the increased incidence of schistosomiasis as a consequence of the enlarged habitat of the kind of freshwater snails that host the parasitic worm responsible for the disease. The definite article is necessary before freshwater snails because the sentence identifies a particular type of snail, namely, those that host the parasite. The correct preposition to express duration in combination with host is for, not in. As the parasite is referred to as singular, the possessive pronoun in the final phrase must also be singular.
A Correct. The sentence is clear with all pronouns and verbs in agreement.
B The preposition in is inappropriate for expressing duration; the plural possessive pronoun their does not agree with the singular antecedent parasite.
C A definite article should precede freshwater snails to identify a particular type of snail; the plural cycles is inappropriate because it. refers to a singular parasite, which only has one life cycle.
D A definite article is needed before freshwater snails; repetition of the word parasite makes the final phrase unnecessarily wordy; cycles should be singular.
E The repetition of hosts makes the final phrase unnecessarily wordy; cycles should be singular; their hosts should be its hosts; the referent for the second appearance of their is unclear—does it refer to snails or the parasite}
The correct answer is A.
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