'For me, it's difficult to learn.'
'To me, it's difficult to learn.'
What's the difference between the above two sentences?
Sorry to have taken so long to answer this, Weibing. As you know, prepositional phrases can often occur either before or after the thing they modify. When you choose to place the PP in the beginning of the sentence, in order to determine which preposition is the correct one to use, switch the order.
"For me, it's difficult to learn."
becomes: "It's difficult for me to learn."
"To me, it's difficult to learn."
becomes: "It's difficult to me to learn."
This should help you determine which prepostion is correct. If we consider the meaning of motion for "to" here, we might think of the the PP as the application of knowledge into my head. However, the expression of motion towards something won't work here, since learning is not actually moving from one point towards or into my head. Therefore, "to" will not work. When we say, "for me", the phrase is actually a shortened form of "as for me", which is used to mean "regarding me", or "as regards me". This works here, since the meaning is one of learning, as far as I am concerned,
or As far as I am concerned, learning is difficult
I have a theory about prepositions that I am in process of researching. Since prepositions basically show relationships, then which ones we use are determined by our basic concept or understanding of different relationships. For example, Americans will speak of what they did "over" or "during" the weekend, whereas a British speaker will speak of "at" the weekend. That is because Americans usually concieve "the weekend" to be a progressive duration of time, whereas a Birtish speaker is more likely to view it as a point in time. This shift in the basic perception of time is what makes someone choose one preposition and someone else another.
Moving from Chinese to English is a good bit more complicated for a couple or reasons. First, English has a lot more prepositions than Chinese does, and many of them have very similar meanings, even when they are used in quite different ways. The second problem involves two very different perceptions of not only time, but also space relationships.
Let us return to your examples. Chinese does not use a preposition for this construction at all. Sorry, I can't type characters, but a gloss of the Chinese, at least for Cantonese, is: "very difficult learn", or "I feel very difficult learn". So, what does the typical Chinese learner do about prepositons? Obviously, simply memorizing all English prepositions together with all their diverse and confusing meanings won't work. First, he has to determine how English percieves the relationship between the act of learning and the fact of difficulty. Also, he must make explicit in English the object "me", which is implicit in Chinese construction.
He has several choices of construction for this.
I think learning is difficult.
I feel learning is difficult.
Learning is difficult for me.
For me, learning is difficult.
As far as I am concerned, learning is difficult.
Once he has established the basic construction he wants to use, then he must determine what, if any, prepositions work in that construction. Notice the first two sentences, which are by far the simplest rendition of the Chinese meaning, have no prepositions at all. If he wants to use a PP, then he has to understand which ones work in the particular relationship.
Perhaps I should halt for now, since this has already turned into a much longer post than I intended. I sincerely hope this epistle is helpful to you, not confusing. Please comment, as I am most anxious for your input concerning this subject.