1. No, you want "at". You also need to fix the agreement of "know"; either "knows" or "knew" would work. Also, be careful about ambiguous attachment of prepositional phrases -- was the consulting or the knowing at the conference? Try using commas and reordering as needed to disambiguate, e.g. "She consulted a senior psychologist whom she knew about the problem, at an international conference last year". 2. "Out of the rubble". 3. It works equally well with or without the article. Most people would omit "whom", I think.

1. It's possible to use 'in', but 'at' is better. We usually use 'at' for events. The main problem with this sentence is the word 'know'. It should be 'whom she met' 2. 'Rubble' is uncountable, so it has no plural form. It would be most natural to say 'pulled the boy out of the rubble.' 3. You can, but it's not needed.

1. You should be able to delete the "whom" from your sentence. "she saw" or "she met" is clearer than "she knew." I understand why you might want to use "in" rather than "at," but "at" is more commonly used and will sound better to your audience. 2. You are correct that it should be written "rubble" and not "rubbles." "Rubble" is a singular noun used to describe a collection of multiple objects. The "the" gives the impression that you are referring to a specific event. If you use the "the" in this sentence it will be assumed that the person you are speaking with is familiar with the place or building from which the firemen saved the child. You often hear this kind of language in news reports where the reporters have already described or shown pictures of the location. 3. The "whom" in this sentence is not necessary and can be deleted. If you wanted to use "the people," you might want to change the words before it to, "please give me a list of the people...." Also, "are going to" is not wrong but it can be simplified as "will," making the phrase, "...you will invite to the party." To make the sentence as clear as possible, I would change it to, "Please give me a list of the people you will invite to the party." Hope this helps.