French language Q&A Forum

Je ai: when we have 2 vowels we use ' so it becomes J'ai so why in Tu as the rule does not apply as we don't write t'as

This weeks Weekend workout (A Lovely Encounter 31-09-2018) asks for a translation of 'She had just closed her eyes when she heard a little squeal comming from the bushes.'

For the 'when she heard' section I answered: 'quand elle a entendu' but the answer was given as 'quand elle entendit' (passé sample). 

Could you please explain why "quand elle a entendu" is incorrect.

Why are quelqu'un, quelqu'une, quelques-uns, quelques-unes left out? These indefinite pronouns are more natural IMO than certain, certains, certaine, certaines and mean the same thing. In both cases you carve out a subset of individuals w/o further identification. Per robert online certain is a synonym. Here is modern and absolute meaning of QUELQU'UN..........