The phrase "comment on the extent" is correct and can be used in written English.
You can use it when you are commenting on the degree, scope, or range of something. For example, "In my opinion, although the new laptop has good features, we should comment on the extent of their power and how reliable they might be."
Neither state agency would comment on the extent of the allegations.
Analysts said Boeing and Airbus probably were giving Emirates significant discounts on the latest orders, though the manufacturers and the airline would not comment on the extent of any reductions.
Anderson and Windsor, whose team is backed by the YouTube co-founder Chad Hurley, declined to comment on the extent of its financial difficulties or of reports that it would probably not be in Bahrain.
Skype told the Guardian that it would not answer technical questions about how it turns over calls to the authorities or comment on the extent of its compliance with US surveillance.
The proposal seeks comment on the extent of separation that would be needed before a related consulting firm could provide otherwise prohibited services to the accounting firm's audit client.
For 1555 AD, Kashmir earthquake more work is required to precisely comment on the extent of surface rupture.
LISA GUERNSEY Correction: June 16, 2000, Friday A report in the News Watch column of Circuits on June 8 about a survey of 500 students on ways in which they used the Internet when selecting colleges included an erroneous reference to its sponsorship and to the role of Richard A. Hesel, who commented on the extent of the students' Web access.
Robert May, the acting chief executive who was recruited as an independent board member after Mr. Scrushy's sale of stock attracted the notice of investigators last year, commented on the extent of Mr. Scrushy's knowledge of the company and his aides' activities -- a crucial question in the government's case.
The final paper in this special issue is a commentary by Elizabeth van Es and Miriam Sherin that discusses the strengths and weaknesses of the papers as well as commenting on the extent to which the overall set of papers as a whole contributes to the ongoing dialogue about video-based PD and its scalability.
During the face and content validation phase of the focus groups, the subjects completed the NPSI and commented on the extent to which the questionnaire captured key symptoms associated with neuropathic pain.
They were asked to comment specifically on the extent to which the program had been implemented in their community and implementation challenges.
