Key to Exercise on Language in Scientific Writing


Each of the following excerpts has an ambiguity. For each excerpt, identify the source of the ambiguity: (1) improper syntax (word order), (2) missing comma, (3) unclear pronoun reference, or (4) grouping of conflicting words. When incorporating this exercise into class, I usually speak for 15 minutes on ambiguities and then pass out the exercise. Emphasize to the students that the point is not necessarily to correct the ambiguity because in some of these excerpts, the intention of the author is difficult to recognize. Rather, the students should recognize the ambiguity and identify what caused that ambiguity. That way, the students will be more sensitive to such mistakes in their own writing.


  1. With the lid off the reactor core was exposed, allowing radioactive isotopes to escape. (missing comma after the adverb "off," pp. 94-95)

  2. We propose to provide the above engineering services hourly based on the following estimates. (improper syntax with the adverb "hourly," pp. 92-93; difficult to revise without knowing author's intention)

  3. Compared with the pollution of the average coal-fired plant, the thermal pollution of a nuclear power plant is less than 2 percent more. (grouping of the conflicting words "less than 2 percent more"; difficult to revise without knowing author's intention)

  4. Reductions up to 80% in heat and mass transfer coefficients were measured due to outgassing. (improper syntax with the prepositional phrase "due to outgassing," pp. 92-93; solution involves rearranging sentence and moving this misplaced phrase next to the noun "reductions")

  5. As airplane designs change the anti-ice systems also have to change. (missing comma after the verb "change," pp. 94-95)

  6. Most people are diagnosed with phenylketonuria at birth. (improper syntax with the prepositional phrase "at birth," pp. 92-93; solution involves moving this phrase after the noun "people")

  7. The use of the thermal storage unit is limited to supplying low-pressure auxiliary steam because of insufficient excess energy from the undersized collector. (grouping of the conflicting words "insufficient excess"; difficult to revise without knowing author's intention)

  8. At this time, the Department of Energy is only considering Yucca Mountain as a possible storage site for nuclear waste. Other possible sites are excluded from discussion. (improper syntax with the adverb "only," pp. 92-93; solution calls for moving "only" immediately after the verb "is considering")

  9. If the airplane waits too long to take off the de-ice fluid can dissipate. (missing comma after the adverb "off," pp. 94-95)

  10. The Lunar Module was only designed to hold two astronauts and to have a life time of forty-five hours. (improper syntax with the adverb "only," pp. 92-93; solution calls for moving "only" immediately after the verb "hold" and immediately after the words "life time of")

  11. The beams are positioned with respect to the chopper blade so that while one beam passes the output of the opposite beam is completely blocked. (missing comma after the verb "passes," pp. 94-95)

  12. The Hindenburg was filled with hydrogen because it is lighter than air...The report claimed that a hull wire could have ruptured a gas cell if it fractured. (unclear pronoun reference because of inconsistent use of the pronoun "it," pp. 93-94; in the first instance, "it" refers to the nearest noun ("hydrogen"), but in the second instance, "it" refers to the subject of the previous clause ("wire"); author either has to develop consistency through the entire document or avoid the conflict by not using pronouns in such situations)

  13. Avoiding complicated multi-ordered calculations, the equations come from fundamental definitions of mass flow, work, and efficiency. (improper syntax with the participial phrase "Avoiding complicated multi-ordered calculations," pp. 92-93; one solution calls for changing the subject to "we" rather than "equations")

  14. To provide spill protection, all tanks were equipped with basins and automatic shutoff devices or overfill alarms or ball float valves. (missing commas in the list of equipment, pp. 94-95; difficult to revise without knowing intention of author)

  15. Being the first step in introducing CFD, Jones had to set up conservative assumptions. (improper syntax with the participial phrase "Being the first step," pp. 92-93; one solution calls for changing the subject from Jones to the name of the first step)

  16. As with any system errors occur in localization. (missing comma after the noun "system," pp. 94-95)

  17. Having a model would help designers predict the effects of engine operation over all speeds. (improper syntax with the prepositional phrase "over all speeds," pp. 92-93; solution involves moving this phrase after the word "predict")



Last updated 3/00
http://www.me.vt.edu/writing/handbook/
http://ae3.cen.uiuc.edu/writing/handbook/
You are more than welcome to use these materials in your classroom as long as you acknowledge the source (http://www.me.vt.edu/writing/).