“Pendant" expresses a global duration of an action which might or might not be continued or repeated. "En" in the temporal context stands for a duration of an uninterrupted action or a time limit is somehow implied.
Sorry if these are wrong but I'm gonna try and help xD
1.) INCORRECT
2.) Henri a besoin d'étudier
3.) Amanda et Carine ont soif
You could say something like "Je pense que ce serait meilleur si les jeunes utiliseraient ses portables moins régulièrement" (I think that it would be better if young people used their phones less regularly) [conditional tense] or "A l'avenir j'espère que les jeunes vont aller à l'extérieur plus" (In the future I hope that young people go outside more) [present and then future] or something about in the past, there not being technology so.. and then expand on the differences? you could say "Quand on était petit" [imperfect tense- past] (when one was younger) to do this, hope this helps :)
