Fixing Dangling Modifiers and Comma Splices
A student is editing a draft paragraph about the discovery of penicillin. The draft contains these two sentences: 'Having discovered penicillin in 1928, the antibiotic’s widespread use did not occur until the 1940s.' And: 'The discovery was accidental, Fleming noticed mold had killed bacteria in a petri dish.' The student wants to fix errors in sentence structure and punctuation without changing the meaning. The teacher has marked the first sentence as having a dangling modifier and the second as a comma splice. The student also wants to combine the two sentences into one clear, concise sentence that preserves the chronological relationship between the discovery and later use. The paragraph will appear in a history essay for a general audience. The teacher wants the revision to be grammatically standard.
1. Identify the dangling modifier in the first sentence and revise the sentence to fix it.
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The dangling modifier is 'Having discovered penicillin in 1928.' It appears to modify 'the antibiotic's widespread use,' but the use did not discover penicillin. The intended subject is Fleming. A revision: 'Although Fleming discovered penicillin in 1928, the antibiotic's widespread use did not occur until the 1940s.' This makes Fleming the subject of the opening clause and removes the dangling modifier.
2. Fix the comma splice in the second sentence and combine both ideas into one sentence that is clear and concise.
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The comma splice joins two independent clauses with only a comma: 'The discovery was accidental' and 'Fleming noticed mold had killed bacteria in a petri dish.' One fix is to use a colon: 'The discovery was accidental: Fleming noticed mold had killed bacteria in a petri dish.' To combine both ideas chronologically: 'Although Fleming accidentally discovered penicillin in 1928 when he noticed mold had killed bacteria in a petri dish, the antibiotic's widespread use did not occur until the 1940s.' This is one clear sentence that preserves the contrast and chronology.
3. Explain why the original first sentence is grammatically problematic, using the term 'dangling modifier.'
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A modifier should describe the subject of the main clause. In the original sentence, the main clause subject is 'the antibiotic's widespread use.' The introductory participial phrase 'Having discovered penicillin in 1928' therefore seems to say that the use discovered penicillin, which is illogical. That is why it is a dangling modifier: the doer of the discovering is missing from the main clause. Revision should supply the logical subject, Fleming.