Nevertheless one had better know the rules, for they sometimes guide in doubtful cases, though not often.

然而一个人最好了解规则，因为有的时候人们会感到迷惑，尽管这种时候并不多。

youdao

Making decisions in doubtful situations for shipping of finished products and the corresponding countermeasures.

在发运中出现可疑情况时，负责做出处理决定和相关的对策。

youdao

The problems lie not only in doubtful blood sources, but also in blood immunology and the quality of blood transfusion.

其影响因素有血源问题，也有血液免疫学因素和输血工作质量问题。

youdao

However spokesman Crowley said interaction between Clinton and her Iranian counterpart in Kabul is doubtful.

VOA: standard.2010.07.16

The solution he proposes shows how much quotas could change Brazilians' sense of who they are: in doubtful cases a commission would verify students' racial identity, overthrowing the idea that a person's race is what he says it is.

ECONOMIST: Race in Brazil

In a careful study, Anthony Cordesman, of the Center for Strategic and International Studies, no friend of Israel, argued that even in the doubtful assumption that such a nuclear exchange could be contained within the region, the resulting horrors would include the deaths of tens of millions and the obliteration of whole societies.

CENTERFORSECURITYPOLICY: Norman Podhoretz receives the Center's Mightier Pen Award

The issue isn't whether the United States will be able to win a popularity contest in the region (this is doubtful even in the best of times), but rather, that alienating large swaths of the local population makes it much more difficult to defeat terrorism.

CNN: Is America the moral leader in the world?