人生沒有用不到的經歷

Lung biopsy is indicated in case BAL cytology is negative for malignancy.
BAL：bronchoalevolar lavage.
對於醫師而言，寫文章時常將 Lung biopsy 及 BAL cytology 抽象化，上例即是某本書上的一個句子：Lung biopsy 及 BAL cytology 之前沒有任何冠詞。

但若你要強調(具體化) BAL cytology 時，可改為 Lung biopsy is indicated especially when the BAL cytology is negative for malignancy.

當你要強調 Lung biopsy時，改為 The lung biopsy is particularly indicated in case BAL cytology is negative for malignancy.

當你要強調 Lung biopsy and BAL cytology時, 改為 The lung biopsy should be done especially in case the BAL cytology is negative for malignancy. 因此, 許多名詞或名詞片語該不該加 the, 只有作者知道. 前面的例子即使不用 especially and particularly, 單加the 同樣能有強調之意.

英語教授則可能這樣寫 A lung biopsy is indicated in case the BAL cytology is negative for malignancy. 他可能把 Lung biopsy 視為一普通可數名詞 (A lung biopsy 意謂 "做一次 lung biopsy" ), 將 BAL cytology 視為一醫學專門名詞 (similar to the liver, the lung, and the brain).

我判斷名詞或名詞片語該不該加 the 有三原則, 供各位參考:

1.該名詞或名詞片語是否本來就該加 the. 例如 This patient had chronic cough for three months. CXR revealled multiple masses on the lung. The result of (a) lung biopsy showed metastatic carcinoma of the breast. The result, the lung 及 the breast 都必須加 the.

2.是否有指定前述名詞或名詞片語: He started a fever in the morning of March 5th. Prior to the fever, he felt chills and headache. the fever 的 the, 用以指定 March 5th 上午的 fever.

3.若無前述兩項，則大多視情況而定，看是否有強調、比較、具體 (而非抽象).
Conduction of the nervous system requires movement of ions across the cell membrane.

The conduction of the nervous system requires the movement of ions across the cell membrane.

Conduction 及 movement 本可視為抽象化的名詞，但若你覺得需要強調二者或其中之一, 加 the 可改變句子的重心 , 但對句意影響不大. (nervous system and cell membrane 如同heart and lung，大多數情況下都必須加the)

怎樣才叫 “強調”？ 舉例而言，Conduction of the nervous system requires the movement of ions across the cell membrane. A rapid influx of Na into a nerve cell, followed by an efflux of K generates an action potential. 此例強調movement，movement 原本很抽象，現在變成具體的鈉與鉀離子在細胞膜內外的移動。

再舉一例：The conduction of the nervous system requires movement of ions across the cell membrane. Its velocity may exceed 100 meters per second, depending on the type of nerves. The fastest one is the giant nerve of the squid. 此例強調conduction.

有些作者使用 the 並不嚴謹，因此寫作中往往不作任何強調，反正也還通順嘛。 因此，盡信書不如無書，即使是 Harrison’s Principle of Internal Medicine (內科學的經典教科書)， 也未必是典範。試想一個 chapter，幾百個 the，一本書幾萬個 the，誰會仔細推敲每個 the？ 「通順」有時比強調「準則」重要。

Sentences from Harrison's Principles of Internal Medicine
Because there are no specific therapies for treatment of ischemic or nephrotoxic ARF, prevention is of paramount importance. (Harrison, 14ed, p1511)  

The treatment of lupus nephritis is controversial and based largely on the class of injury and disease activity. (Harrison, 14ed, p1549)

第一句treatment之無the，第二句treatment之前有the，許多初寫文章的研究者常因此困擾，希望找出一個規則。上面兩句是否要加the，完全在於作者對treatment 之認定。第一句作者 "主觀地" 認為 “此處” 的 ischemic or nephrotoxic ARF 不需特別強調 (或指定) 其 treatment；第二句作者 "主觀地" 認為 lupus nepritis 需要特別強調 (或指定) 其 treatment。若我是作者，兩句treatment之前，我都會加the。事實上，兩句treatment之前有沒有the，並不影響句意，也無所謂對錯。treatment 本就有抽象之意 (看不見、摸不著、不能吃、不能用) 不加冠詞本就理所當然。各位不妨參閱文法書，普通名詞之前通常要加冠詞，抽象名詞之前通常不加冠詞 (e.g. Prevention is better than treatment). 但抽象名詞若有所指定，則應視情況加上冠詞 (e.g. The treatment of DM is a teamwork, involving doctors, nurses, dieticians, social workers, and patients' family)。

He is lying on the bed. (不能寫成 He is lying on bed.)
He fell to the ground. (不能寫成 He fell to ground.)

但有時小說作家卻不拘泥文法: Tom felt so sorry to his girlfriend. Lying on bed, he was puzzled how to deal with the trouble he made.