Hi masaegu san, thanks for explain it to me. I think I know what you meant by "pronounced with a striking difference". For example, when I say "私は田中です", I will say with a normal tone, whereas I will say with a firm tone like "私が田中です" albeit without shouting. :)

Under one condition, you could answer that question with 僕は行きます. The condition is that the other person states that he needs a couple of guys to go before he asks "Who will go?". Still, I would think that more of us would say it with が. Then a second person would say it with も.

は can imply "at least" when used in certain types of context, but the context that we are discussing is not quite one of them. When you say something like "Kansas City has A and B, but not C or D.", は would come in handy. 「カンザス・シティーにはＡとＢはあるが、ＣとＤはない。」 In this sentence, the は in red can imply "at least".

I'm not sure if one could safely say that we prefer using は in negative phrases because we often use が in negative phrases as well that could not be replaced by は.　e.g. 「今年は雨があまり降らなかった。」、「バスが来ない 。なんで？」、「ボブが見当たらない。」, etc.　

Speaking of "は" and "が', there is something that confuses me.

For example:

金はありますか？

金がありますか？

金はありませんか？

金がありませんか？

I know those sentences above are pretty easy for most people to differentiate which is correct and which is wrong but somehow I still confused by it.

Even though these phrases have been given without context, the following CAN be said.

All are correct and natural. The differences are in the connotation.

は = money in general

が = specific amounts of money.

お金が　＝　そのお金が. Both speaker and listener know exactly the amount in question.

お金は　≠　そのお金は. No specific amount has been mentioned.

Hi masaegu san, how about things like car, computer, etc?

It all depends on the context, not the noun used as the subject. There are situations (context) when は and が are interchangeable to an extent with only a slight difference in the nuance, which is basically the case with your sentences about money above. "I have money." vs. "I have the money." However, the は and が aren't at all interchangeable in your sentences about Tanaka.

I know it's frustrating to you but it will take a few years for anyone to start using those two particles correctly over 70% of the time, let alone 80. :)

Thanks masaegu san. I think I need more time to figure out all these particles. :)

Hi masaegu san. I have a question regarding the sentences above. What if I am alone in the class and 先生 ask me who is Tanaka (in this class)? Should I still answer "私が田中です" or "私は田中です"?

That's definitely が. It doesn't matter how many people are in the room.

Thanks masaegu san. By the way, what does "ボブが見当たらない" mean?