as I always have had a hard time figuring out, when to use commas in English, I would like you to have a look at the following sentences and tell me whether the commas are correct or not.

  1. Based on the literature review, Section 2 identifies the objetivces of this study.
  2. The electrical load is reduced, leading to lower costs.
  3. This study shows the disadvantages of the traditional methods and thus, the need for new methods
  4. Besides energy storage systems for storing electricity, such as batteries, flexible loads are necessary for integrating renwable energy sources. [both commas]
  5. The device has an electrical power of 2000 W, which can be adjusted continuously.

I'd appreciate every comment.

  • 1
    (1) correct (2) optional (3) dubious (suggest no commas, comma after methods, or commas round and thus, in that order of preference) (4) needed (both commas) (5) optional, but I'd use it. Apr 7, 2020 at 14:17

1 Answer 1

  1. The comma is needed here as the participial phrase is non restrictive. This is explained here.

  2. As in "1." above, the comma is necessary (same reference).

  3. A perusal of the books from the ngram "and thus" shows two solid trends: ", and thus …" and "no comma at all". The possibility " and thus," is not found and there are some rare cases of ", and thus," and " and, thus, " (those latter two might be acceptable). It would seem that " and thus," does not reflect a meaningful partitioning of the sentence in syntactic groups, and I would avoid it.

  4. There tends to be no comma when the concept exemplified by means of the "such as" phrase is represented by a noun or short noun phrase preceding it; otherwise, commas are used to set off the "such a" phrase. Therefore, the commas seem justified here.

  5. The comma in "5" is what makes the difference between a descriptive (also called non-restrictive) and a restrictive clause. As the restrictive "mode" (no comma) is not pertinent (no such defined powers in EE) the descriptive case (comma) is realy what is needed. These notions can be verified here.

  • Thanks LPH for your answer. Regarding point 4 and such as: If I use an enumeration do I have to use commas before 'such as'. Example: Developed countries, such as Germany, France, and Spain. --> Are all commas necessary in this case?
    – PeterBe
    Apr 7, 2020 at 17:39
  • 1
    @PeterBe No, according to what the books show the best is to use no comma, but it seems to me that the use of a comma wouldn't stand out as an odd occurrence (there are cases of it in the literature). "Developed countries" is a short phrase.
    – LPH
    Apr 7, 2020 at 17:51
  • Thanks for your comments LPH
    – PeterBe
    Apr 8, 2020 at 14:11

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