為什麼這裡用現在分詞，不用動詞?

The answer must be (A) only, according to the meaning of the sentence.
發現的是 "罪魁禍首" - the culprit causing the problem
發問者想到的一個 觀念是對的 (是因為省略了關係代名詞)

*** critical thinking should make things clearer but not create more confusion. (Be objective...!)
因 - printers have defects
果 - printers shut down without warnings
先出現原因然後找出結果，是對嗎?


If (D) can also be selected, the sentence should be like:
The researcher discovered (that) a critical defect forced the printers to shut down without warnings.
reason: "the" critical defect (as well as the phenomenon of printers' shutdown) is unknown before it was discovered, so indefinite article "a" should be used.

*** quoted from some grammar page ***
(Nouns in English are preceded by the definite article "the" when the speaker believes that the listener already knows what he is referring to.)

If the critical defect is already known, the sentence should be like: (for choice of D)
The researcher discovered why/how the critical defect forced the printers to shut down without warnings.

If 發現的是"defect"所造成的症狀, the main verb of the that-clause should be in "modal", like:
The researcher discovered (that) the critical defect would/should force the printers to shut down without warnings.

你剛剛想到的原句 只是其中的一個可能性而已:

1. 原句 (X):
The researcher discovered the critical defect that forced the printers to shut down without warnings.

2. 原句 (Y):
The researcher discovered that the critical defect forced the printers to shut down without warnings.

這兩句的不同在於:
(X) 發現的是"defect"本身的存在
(Y) 發現的是"defect"所造成的症狀

3. 你覺得 你的原句

The researcher discovered the critical defect forcing the printers to shut down without waring.
是由(X)來的呢? 還是由(Y)來的?


4. 你原來的問題 的答案應該是 (A)(D)都可以.
在某些情景之下,(D)是可選的 因為

原句 (Y)的 that是可以省略的. that is:


The researcher discovered that the critical defect forced the printers to shut down without warnings.
and
The researcher discovered (that) the critical defect forced the printers to shut down without warnings.

are both fine.

(B)不能選是因為:
(B1)不應該用現代式
(B2)就算是要用現代式 也應該+s (三單)

5. 冠詞的應用,本來就多決定於上下文所描述的情景

例子:
Three defects were reported from the field - one critical and two minors. The researcher discovered (that) the critical defect forced the printers to shut down without warnings... (O)
Three defects were reported from the field - one critical and two minors. The researcher discovered (that) a critical defect forced the printers to shut down without warnings ... (X)

請多用critical thinking的方式來思考. 不要去相信 那些 "見樹不見林"的爭論.

The researcher discovered the critical defect ____the printers to shut down without waring.
其中用現在分詞forcing或過去式forced都對，但二者之間要選一則forcing較佳,我的理由是現在分詞表一段時間，因印表機故障已持續一段時間後才被發現，若用簡單式則只是一個事實，且分詞有強調語意

我再舉個例子：He came home while I was cooking.若寫成He came home while I cooked.都對，但以第一句較佳