I need some help on a grammar worksheet for college english...?

I answered the ones i was certain on... but there are still some im having trouble with. If you could please help me out. Its on subject-verb agreement thats confusing the heck out of me. I'll say what I think it is if you could explain why its right or wrong. THANK YOU SO MUCH! (=
1) The complaints and challenges from the opposition this past congressional session ?(has or have)? frustrated the senator.
2)There ?(is or are)? altogether too many reading and writing assignments for the average sophomore in the course.
3)The number of people still confused about the transmission of AIDs ?(defy or defies)? all efforts at education.
4)Home economics, especially nowadays, ?(involve or involves)? more complex principles than most people realize.
5)Among the exotic fruit at the market ?(was or were)? the kumquat and casaba melon.
6)All of the produce brought in this morning by trucks ?(remain or remains)? available in the bins.
dang. it wont let me type more. posting another one ...

1. This is plural, so you use 'have' as in 'they have'
2. Again, assignments is plural so you use 'there are'
3. This one is tricky. The referent here is 'the number' not 'people' so it is singular - the number defies.
4. Home economics is the name of a high school level course and if it is used in that context, it is singular. Home economics, as it refers to what is practised in homes across the nation, is a plural word that covers cooking, sewing, cleaning, budgeting, etc.etc. so in that context, it is plural.
It's hard to say exactly which usage is meant in this sentence, but I would opt for the plural and say 'home economics involve' but you could equally well argue for 'home economics involves' depending on the paragraph in which this sentence is embedded.
5. Well, this sentence is wrong. If you want to indicate there were different kinds of exotic fruit, you would have to say 'Among the exotic fruits at the market were kumquats and casaba melons.' Among the exotic fruit doesn't make sense because 'fruit' is not one of those words that is both singular and plural, like 'moose' is. More than one fruit is referred to as 'fruits'

I'm not going to check your next one - the secret to these is to figure out EXACTLY which word the verb is acting with, and match the singular and plural forms.

1)has
2)is
3)defies
4)involves
5)were
6)remain

1. The complaints and challenges ... have
2. There are ... too many assignments
3. The number ..... defies
4. Home economics .... involves
5. Were .... (It is actually "The kumquat and casaba melon were"
6. All .... remains

Hope this helps.