Are the commas used in these sentences correct?

Question

Is the use of commas in these sentences correct?

1. Quasi-static and dynamic tensile tests were conducted on Spectra® 900 yarns, up to a strain rate of about 500s-1, and at temperatures of 20°C, 40°C and 60°C.

The comma before 'and' was added by my Prof. Is it necessary?

2. The average error between the theoretical transverse wave front velocities required for calculation of the instantaneous modulus of 235GPa (446m/s and 565m/s for impact velocities of 100m/s and 150m/s respectively), and the maximum transverse wave front velocities obtained by observing the progression of the transverse wave front (underlined in Tables 5.4, 5.5), is 2.34%.

The two commas are used because the sentence is very long and I'm trying to break it up into parts. However, is the usage correct?

3. Application of this method to the results of finite element simulations of tensile Hopkinson bar tests on a simple elastoplastic material, and experiments on Spectra® 900 yarns using specially-designed impedance-matched grips, confirmed the validity of the method.

Commas are again used to beak up the sentence. Correct?

Answer 1

Other than the comma between 20C and 40C, none are needed or correct in any of the sentences. I have no idea why your Prof added a comma before "and" in #1. Both it and the one between "yarns" and "up" should be deleted.



In #2 and #3, you have placed commas between the subjects and verbs--a real no-no. If the sentences seem too long and complex, you might want to divide them each into 2 sentences.



Of course, you could divide them into a dozen sentences and I would still have no idea what you're talking about. Very impressive subject matter.

Answer 2

I tried to explain this to you when you first posted the question, so this time I'm just going to refer you to 2 websites that agree with each other and clearly explains when to use commas:

http://owl.english.purdue.edu/owl/resource/607/02/

http://grammar.ccc.commnet.edu/grammar/commas.htm



At no point does either website say simply that "commas are used to break up sentences." That's an oversimplification. Just as your scientific experiment has its precise rules, so does the English language--and putting commas wherever one pauses or wherever one feels like it is not one of them. If you have an excessively long sentence that is unclear, the magic fix is not a comma; instead, find a logical place to break the sentence into smaller components.

Answer 3

Your use of commas in these sentences is correct usage. In all cases, if you did not use those commas where they're placed, it would be much more difficult to follow the sense of the sentences. In the first sentence, where your professor added a comma, I think it was to keep all those numbers straight.



Good job!

Answer 4

sentence 2 & 3, commas use is exactly correct.

In sentence 1, the comma between "yarns" and "up" is not necessary, but you need to add a comma after 40*C, (I know that's supposed to be a degree mark, not an asterisk, but you get the idea).

Answer 5

According to John, the flight consisted of expert Marine Corps aviators. Who, after reporting a number of odd visual effects, simply disappeared. An account which isn't entirely true.