1、指代不同
be weak in：差，不擅长于什么什么。
be weak at：软弱的，较差。
2、语法不同
be weak in：接表示事物的名词、代词、带疑问词的动词不定式、that或疑问词引导的从句作宾语，或动词不定式充当补足语的复合宾语。
例句：
You must be weak in the head if you think I'll agree to that.
如果你以为我会同意那事，你一定是脑子不管用了。
be weak at：接名词或代词作宾语。也可接以形容词充当补足语的复合宾语。
例句：The researches at home and abroad on interpersonal self，howeve appear to be quite weak at present.
但目前国内外对人际自我的研究还显得十分薄弱。
3、侧重点不同
be weak in：指在某个领域不擅长。
be weak at：指在某个学科较差。
be weak in相似短语
1、be weak of在…很弱,不善于…
2、be weak on在…很弱,不善于…
3、be weak in差,不擅长于...
4、as weak喝得酩酊大醉[穷得身无分文,弱得毫无气力]。
5、weak weld不强固焊缝。
6、as weak as water adv.极虚弱。
7、a weak link薄弱环节。
8、leptonic weak process轻子弱过程。
9、inorganic weak acid无机弱酸。
10、weak external reference弱外部引用（=WXIRN）一种在连接编辑过程中不必求解连接的外部引用。当没有对这种引用进行求解时，则其值被视为零。
be weak in相似单词
weak a.1、不牢固的，易破的，易坏的；易弯曲的。2、（身体等）虚弱的，无力的；（器官）功能差的，受损伤的。3、意志薄弱的；懦弱的，无决断的。4、（能力等）弱的，差的；（资源等）缺乏的；（船等）。
weak headed a.易醉的,懦怯的,优柔寡断的。
weak minded a.低能的,懦怯的。
weak eyed a.视力差的。
weak spirited a.缺乏勇气的。
weak kneed a.膝盖弱的,软弱的,优柔寡断的。
weak willed a.意志薄弱的。
weak stemmed n.有一个弱茎。
we pron.1、我们，咱们。2、人们。3、朕，寡人(指皇帝、女王或教皇的自称)。
be weak in双语例句
1、You must be weak in the head if you think I'll agree to that.
如果你以为我会同意那事，你一定是脑子不管用了。
2、The students were found to be weak in sports skills and in lack of understanding of sports.
贫困生体育行为的显著特点是对体育的认识不足，在体育技能方面偏弱。
3、The resulting melamine-tainted feed would be weak in protein,he acknowledged,which means the feed is less nutritious.
被三聚氰胺污染饲料就会削弱蛋白质的营养成分，他承认，这意味着饲料的营养更少。
4、Some dealers were believed to be weak in terms of professional management capabilities and were thought to be under-exploiting the sales potentials in their territories.
一些经销商被认为在专业管理方面薄弱，而且在其管区内未能达到应有的销售潜力。
5、If the fibers are placed parallel to each other,the finished fabric will have good strength in that direction but will tend to be weak in the opposite direction.
如果纤维是相互平行的，织物沿纤维方向会有较高的强度，而在与纤维垂直的方向强度会较低。
6、This cannot the completely strange public's legal awareness be weak,in theirs experience,the what one sees and hears power was bigger than method the phenomenon are too many.
这不能完全怪公众的法律意识薄弱，在他们自己的经历中，耳闻目睹权大于法的现象太多了。
7、They'll mete out more damage than any other class,but will be very weak in melee situations,wearing only cloth armor.
他们能造成比其他任何职业都要大的伤害，但在肉搏战中将会非常脆弱，因为他们不能穿甲。
8、People can be a weak link in an otherwise secure network.
人们可以在一个安全的网络，否则的薄弱环节。
9、Besides,the research of dialects spots remains to be a weak link in dialect study.
另一方面，汉语方言点的研究也一直是方言研究的薄弱环节。
10、This,however,remains to be a weak link in the planning and management in the geological trade as a whole.
而目前这方面在整个地质行业计划管理中还是个薄弱环节。
be weak at双语例句
1、OECD chief economist Jorgen Elmeskov says it might be premature to declare a recession in the United States.But at a press conference in Paris,Elmeskov said the U.S.economy would be extremely weak for at least the first half of this year,hampered by a credit crunch and the collapse of the U.S.housing market.
该组织首席经济学家埃尔姆斯克夫说，现在就认为美国进入经济衰退还为时过早，但是他在巴黎举行的一次记者会上说，美国经济在信贷紧缩和住房市场崩溃的影响下，至少在今年上半年将极其衰弱。
2、But now I come to realize that however strong-willed a person is,he will be weak at some time,or at some point.
但是，如今我意识到，无论一个人再怎么坚强，他总会有脆弱的时候或是弱点。
3、The researches at home and abroad on interpersonal self,however,appear to be quite weak at present.
但目前国内外对人际自我的研究还显得十分薄弱。
4、Therefore it can be weak against infantry at close range,meaning that city and forest areas should be avoided wherever possible.
因此它对于步兵的近身攻击毫无免疫力，这意味着在城市和森林中作战的时候无论什么情况下都要避免可能存在的麻烦。