"I know her."
Translation:Je la connais.
I looked it up here: http://french.about.com/od/grammar/a/savoirconnaitre.htm I suggest you look at this rather than me paraphrasing it, as I won't say it as well.
With people and places, please use "connaître": je connais cette personne; je connais la Normandie.
With the meaning of "to be familiar with/to be knowledgeable about/to be aware of", "connaître" is also the correct verb: je connais l'histoire de mon pays; je connais beaucoup de mots anglais; je connais ses méthodes.
You will use "savoir" with things you have learned, before any verb in the infinitive and any subordinate clause: je sais lire/écrire/compter/nager; je sais que la terre est ronde.
Lui, personal pronoun, can be two things:
indirect pronoun standing for "à + il" and "à + elle": je lui donne, je lui parle, je lui dis, (verbs: donner à, parler à, dire à...)
stressed pronoun of "il":
-- after a preposition: Je vais avec lui
-- as a compound subject: Lui et moi sommes amis
-- as part of a short answer: Qui est là ? C'est lui !
-- as an apposition: Lui, c'est lui, et moi, c'est moi !
Note: the stressed pronoun of "elle" remains "elle": Je vais avec elle - Elle et moi sommes amis - Qui est là ? C'est elle ! Elle, c'est elle, et moi, c'est moi !
It was multiple choice - as knowing a person is 'connaitre' I picked that as the only true answer. Instead I found that using 'saisir' was also correct. In another exercise, they were clearly not equal to each other. It would be nice if the lessons that we are learning are coherent all the way through the exercises!
This verbal form does not exist.
You can find inversions with [Verb-hyphen-dummy T-hyphen-pronoun], but only in questions.
For instance: Aime-t-elle mon repas ? = Does she like my meal?
This sentence is a statement and "her" is the direct object of "know/connais". So you need the direct object form of "elle", which is "la" (= her) and you have to place it in front of the verb: "Je la connais".