A：seem, appear 和 look 在英文中叫做連綴動詞 (copular verbs or linking verbs)，其後接形容詞 (或名詞或名詞片語) 來做主詞補語。例如：
- He seems angry. (他似乎生氣了)
- John appears unaffected by all the media attention. (約翰似乎未受媒體關注的影響)
- She looks very happy. (她看起來非常高興)
注意：連綴動詞後面要接形容詞，不可接副詞，所以下句是錯誤的：
- She looked angrily.
當然啦，若 look 不是用作連綴動詞，而是當一般動詞用，意為「看」，那麼就可用副詞來修飾 look，如 She looked angrily at the intruder. (她憤怒地看著闖入者)。
首先來看 seem, appear 和 look 的語法結構差異：
1. Look 和 seem 後面可接 as if/as though 或 like 所引導的子句 (like 後面亦可接名詞或名詞片語)，但 appear 通常不行。例如：
- It looks as if it’s going to rain again. (看來好像又要下雨了)
- It looks like David will be able to come too. (看來大衛好像也能來)
- It seems as if they’re no longer in love. (他們似乎不再相愛了)
- It seems like their marriage is over. (他們的婚姻好像結束了)
2. Seem 和 appear 後面經常接「to + 原形動詞」的不定詞結構，或者接「to + have + P.P.」的完成式不定詞結構來表示該完成式動作或狀態比 seem 和 appear 還要早發生或出現，但 look 則沒有這項用法。例如：
- It seems to rain all the time here. (這裡好像一直在下雨)
- I seem to have lost my way. Can you help me? (我好像迷路了。你能協助我嗎?)
- My boss seems not to like the idea. (我老闆似乎不喜歡這構想)
= My boss doesn’t seem to like the idea. - No one appeared to notice me. (似乎沒有人注意我)
- They appear not to be at home. Nobody’s answering. (他們好像不在家。沒有人應門)
= They do not appear to be at home. No one’s answering.
(由例句可知，seem 和 appear 的否定形式有兩種，—是將否定詞放在 seem 和 appear 之前，另一是將否定詞放在 seem 和 appear之後的不定詞之前，但意思不變。)
3. It seems… 和 It appears… 後面可接 that 所引導的名詞子句，但 It looks… 則不行，後者只能接 as if/as though 或 like 所引導的子句。例如：
- It seems (that) there is no way out of our difficulty. (我們似乎無法擺脫困難了)
- It seems to me (that) it will rain tonight. (我看今晚會下雨)
- It appears (that) I was wrong. (看來我是錯了)
- It appears (that) she has changed her mind. (看來她已改變心意)
Seem, appear 和 look 均意為「似乎，好像，看起來」，但他們的語意不盡相同。Seem 可用來指比較客觀的事實、印象或感想，亦可用來指比較主觀和情緒上的印象或感想，而 appear 是個比 seem 略微正式的字，通常只用來指比較客觀的事實、印象或感想。Look 的用法與 seem 相近，用來指從外表得到的印象或感想，因此所做出的判斷有可能與事實相符 (客觀的事實)，也可能與事實不符 (主觀和情緒上的印象或感想)。
就比較主觀和情緒上的印象或感想而言
- It seems a shame that we can’t take Linda on holiday with us. (不能帶著琳達跟我們一起度假似乎很可惜)
- It doesn’t seem like a good idea to leave him here by himself. (讓他獨自一人留在這裡似乎不是個好主意)
- It seems ridiculous that he has to stay here to look after the cat. (他必須留在這裡照顧貓似乎很可笑)
就比較客觀的事實、印象或感想而言
- They have the same surname, but they don’t appear/seem to be related. (他們的姓氏相同，但似乎沒有親戚關係)
- She’s not getting any better. It seems/appears that she’s not been taking the medication. (她的病情沒有任何好轉。她似乎一直都沒有服藥)
最後要注意的是，seem 僅能當連綴動詞用，而 appear 和 look 還有其他意思和用法。