About Relative clauses Q 1) The bat is the only mammal (that/which) can fly. ==>Can I use which for animals? how about who? Q 2) The teacher (that,whom) I like the most is Mrs. Grange.                 Mr.Green is the man (that,who,whom,nothing) I was talking about. ==>Two sentenses are from my textbook. I don't know why I can't use 'who' in the first sentence. ==>I know some of relative clauses can be missed(?) in a sentense, but I don't know the exact rule. Please let me know when can I left them out of a sentense? Every relative clause can be left out?(I mean ellipsis) Q 3) "Money and Information" IS(or ARE) really important" Which verb can I put in the sentense, is or are ? Both money and information are noncountable noun, but there are two noncountable word"S"... So... Please let me know Q 4) "Hunger and Poverty are(is?) worldwide problems to which solutions must be found." In this sentense, I couldn't figure it out the meaning of "TO WHICH" if the sentense was "Hunger and poverty are worldwide problems to the thing that (what) solutions must be found." , I would have no prolbem to figure it out. Please explain me about it. Q 5) Please just let me know. in which = where ? at which = when? to which = ? else? Would it be better idea if I understood them as a idiom , or I'd better figuer it out how did it go to the meaning? Q 6) People about whom the novelist wrote were factory workers and their families. Same as my question 2.   if the sentense was "People whom the novelist wrote about were factory workers and their families" , I would understand it easily... Please explain me why did they write like that and what's the difference. Q 7) " He asked me what I like to listen to " " He asked me what I liked to listen to" Which one is correct ? "He asked me why I dion't(or didn't) go to the gym... Please let me know which one is correct. -I will really appriciate if I get clear answers. Thanks-