Traditional language teaching uses word meanings to
assign parts of speech, but this can easily lead to mistaken concepts. Let's
use the traditional definitions of nouns and verbs as examples: 傳統語文教學用詞義來確定詞類，可是這樣做容易引起錯誤認知。我們先拿名詞和動詞來說：
1
A noun is the name of person, place, or
thing 名詞是人，地方或東西的名稱
2
A verb is an action word 動詞是代表動作的詞
The traditional definitions of English parts of
speech seem very simple and easy to understand, but they are hard for Chinese-speaking
students to use (even native speakers of English occasionally have trouble
applying these rules). Take for example, "Playing chess takes concentration." Concentration does
not feel like "the name of a person, place or thing." Furthermore,
the Chinese translation of "Playing chess takes concentration" uses a what feels like a verb instead of a
noun, so a careless student might wrongly assume that concentration is indeed a verb. A similar example is a Chinese
student's translation of 他不怕餓: He is not afraid of hungry,
where the very common word 餓
is rendered by the very common English adjective hungry (not many beginners are aware of the noun form hunger).
以上對詞類的傳統定義看起來簡單易懂，但事實上操漢語的學生不容易使用（連母語人士也會有困擾），例如 “Playing
chess requires concentration”（下西洋棋需要專心）。許多學生有壞習慣，靠中文翻譯來記英文字義，拿中文詞類當英文詞類，『專心』不是『人，地方或東西的名稱』所以不像名詞，比較像動詞，但英文的 concentration 是名詞。類似的例子很多，例如：他不怕餓 ≠
He is not afraid of hungry （應該是 Hunger doesn't bother him OR He's not afraid of going hungry)。
Modern linguistics uses more reliable criteria for
deciding on parts of speech, morphology (word shape) and syntax (word position
on a sentence). 現代語言學對詞類的區分有更可靠的標準：形態和語法.Here are some examples:
Morphology: The shape of
a word, especially the ending, often makes it easy to recognize its part of
speech. Thus for example, concentration
and freedom are nouns, concentrate is a verb and freely
is an adverb.
形態：看單字外表，尤其是字尾，比較容易辨別詞類。例如：concentration和freedom都是名詞, concentrate是動詞，hungry是形容詞，freely是副詞）
Syntax: A sentence
pattern (the position of a word in a sentence) is another easy way to recognize
a word's part of speech. In Playing chess
requires X, and Y
doesn't bother him, X and Y can only be nouns, so concentration and hunger
must be nouns. In He's not afraid of
going Z, Z can only be an
adjective, so hungry must be an adjective.
語法：看句型（單字在句中的位置）也很容易辨別詞類。“Playing chess
requires X”，“Y doesn't bother him”：根據位置，以上兩句的X和Y只有名詞可以充當，所以concentration和hunger一定是名詞。 “He's
not afraid of going Z”：根據位置，前一句的Z只有形容詞可以充當，所以hungry一定是形容詞。
