越簡單的觀念反而越容易被忘記或忽略~~10點感謝

你好，

有時候it跟this/that是可以替換使用的沒錯，比如說: Whose book is this/that? 跟 Whose book is it? 是可以替換使用意思也是一樣的，因為所指的都是同一樣東西,沒有爭議。不過有時it跟this/that是無法互相替換使用的，問題出在it可以當事或物的代名詞，而this只能當物的代名詞。

I am writing a journal for my English paper. My teacher says "it" is a good way for me to practice writing in English about my experiences there in the U.S.

這裡會用it是因為writing a journal是一件事或一個動作，所以用it代稱。如果換成this的話，就變成是指journal而已，而journal無法是a good way for me...，也就是writing a journal可以是個好方法，而單單journal無法成為好方法。

Helen made a vow that she would become an excellent cook in the future, and she considers "this" a serious promise that she must keep.

而這裡會用this是因為所代稱的是前面的a vow，"她認為這個誓言是一個嚴肅的承諾"，所以this=a vow。這句話裡面如果把this換成it變成...she considers it a serious promise...，意思稍稍有改變而成為"她把發一個誓這件事認為是一個很嚴肅的承諾"，此時it=making a vow。

所以，總結來說，this/that是代名詞沒錯不過取代的都是某個名詞，而it可以取代名詞也可以取代一件事。端看你需要的意思而去做取捨。

以上，希望清楚! ^^

This is good for you. 這對你是好事(指定是單純一事)
It is good for you. 那對你是好事 (前面講過的一串事)
第一句的 it= writing a journal for my English paper (不能用this代替)
第二句的 this= vow / 換成 it 要+ is= become an excellent cook in the future
@this 或 it 意思差很多 ~~請注意優~~
PS: I am writing a journal for my English paper. O美國訓練英文都是寫journal

請參考

it~pron.
1.a thing, situation, person, or idea that has already been mentioned:

Did you bring your umbrella? No, I left it at home.




2. the situation that someone is in now:

How's it going, Bob?




3. used as the subject or object of a sentence when the real subject or object is later in the sentence:

It costs less to drive than to take the bus.




4.used with the verb~be to talk about the weather, time, distance etc:

It's raining again.




5.used to emphasize one piece of information in a sentence:

I don't know who took your book, but it wasn't me.
個人認為此項可以為你的第一個疑惑解答，在句子裡用來強調某些訊息，老師要強調寫日記這件事(訊息)對你練習寫英文很有幫助。




6. used as the subject of the words~ seem,appear , look, and happen:

It looks like Henry's not going to be able to come to lunch.




7.It's me./ John/ a pen etc.
used to give the name of a person or thing when it is not already known.

Who's on the phone?　It's Jill.





This : determiner,限定詞/ pron

1.used to talk about something or someone that is near to you:

My mother gave me this necklace.





2.used to talk about the present time or a time that is close to the present:

What are you doing this week?





3. used to talk about something that has just been mentioned or that has just happened: (for your second question)

I' m going to make sure this doesn't happen again.

你的第二個問題，this 來代替前面所提過~ 宣誓這件事或才剛剛發生的事



PS: 請要小心不要掉入中文的思考模式裡，否則就不能寫出正確道地的英文。

個人認為版大的想法在文法上是O.K.的，只是所傳達的語氣不同。it及this都可做代名詞用，但this是指示代名詞，感覺上有點兒強調，也更清楚
另外這句"I am writing a journal for my English paper."有點看不懂，是否應為 I'm writing my English paper(essay) for a journal.?否則好像會讓讀者以為"我為我的英文論文寫一本雜誌"！不知是否誤解了原意？