1

The following three sentences appear in the same published paper. Why does No. 1 employ the auxiliary "did" whereas the other two omit it?

  1. This could explain why ProRoot WMTA showed significantly darker discoloration than did Angelus WMTA.

  2. Groups 1 and 2 showed significantly greater discoloration than Groups 3–5.

  3. However, PC+BO contained 20% bismuth oxide and showed significantly less discoloration than the two WMTA formulations.

Improve this question
1
  • 2
    In 'John knew more anglers than the two living next door', a 'did' would obviously disambiguate. The 'do' etc is often dropped when ambiguity isn't an issue. I'd say it could be dropped in your first sentence (someone could just about, I suppose, imagine that 'Angelus WMTA' was a shade like '6D3 F20', though the previous 'WMTA' shows it's not).
    – Edwin Ashworth
    Jan 10, 2015 at 11:53

1 Answer 1

Reset to default
1

As suggested in the comments, there's no reason in these sentences to include or forego the "did". If you compare them with and without, you can see that there's no real difference, other than to disambiguate subject and object in more complex cases.

1a. This could explain why ProRoot WMTA showed significantly darker discoloration than did Angelus WMTA.

2a. Groups 1 and 2 showed significantly greater discoloration than did Groups 3–5.

3a. However, PC+BO contained 20% bismuth oxide and showed significantly less discoloration than did the two WMTA formulations.

1b. This could explain why ProRoot WMTA showed significantly darker discoloration than Angelus WMTA.

2b. Groups 1 and 2 showed significantly greater discoloration than Groups 3–5.

3b. However, PC+BO contained 20% bismuth oxide and showed significantly less discoloration than the two WMTA formulations.

Improve this answer

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.