Is it correct to use both past and present tenses in sentences where experiments lead to the discovery of general truth about smth, like this: "Experiments demonstrated that in this solution technetium desorbs from sorbent."
2 Answers
There should be no problem with mixing present with past, as long as you don't do it unnecessarily. The sentence is OK, but you could use the perfect to give the idea that the results of those experiments are still important today. Past simple would be the best choice for obsolete experiments and results (e. g. an experiment that suggested the existence of the Ether)
Certainly. We do this all the time. In the simplest case, "Yesterday I went to the store and tomorrow I will go to the zoo." Two different events happening at different times. In other cases the events are tied together. Like, "Tomorrow I will tell Bob that his house burned down yesterday." The burning down happened in the past so is in past tense. The telling is in the future so is in future tense. There's nothing unusual about mixing tenses like this at all. Just be sure to put each event in the correct tense.
