Please capitalize where necessary: ... an ardent correspondent both to individuals and newspapers and many penetrating and sensible letters of his appeared in the times.
A: ... an ardent correspondent both to individuals and newspapers and many penetrating and sensible letters of his appeared in the Times.
Q: did someone email you a hpgl file and you're not sure how to open it? maybe you have found a hpgl file on your computer and wondering what it's for? windows might tell you that you can't open it, or in the worst case, you might encounter a hpgl file related error message.

A: Did someone email you a HPGL file and you're not sure how to open it? Maybe you have found a HPGL file on your computer and wondering what it's for? Windows might tell you that you can't open it, or in the worst case, you might encounter a HPGL file related error message.
Q: saturday 10 february, 2018 61832970 requests since tuesday 16 december, 2003
A: Saturday 10 February, 2018 61832970 requests since Tuesday 16 December, 2003
Problem: such differences in trading hours depend on the individual schedules of major exchanges.
Can you repeat this sentence, but capitalize it?
Answer: Such differences in trading hours depend on the individual schedules of major exchanges.
Text: this works even with oak, which contains water-soluble tannic acids and is extremely difficult to coat.

Correct capitalization: This works even with oak, which contains water-soluble tannic acids and is extremely difficult to coat.
Text: have you already heard much about how botox can remove wrinkles, but don't quite dare to get a treatment?

Correct capitalization:
Have you already heard much about how Botox can remove wrinkles, but don't quite dare to get a treatment?