跪求以下題目的英文文法解說

1. ________ you are in the world of business or the world of social relations, the way you dress can make a tremendous difference.
A)No matter B) Whether C) Although D) Either
根據句意要選"不論"，你可以說no matter whether，也可以只說whether
所以選B


2. To some people, Mickey Mouse is seen as the spread of American culture to other countries ________ he reflects American imperialism and ideas.
A) when B) what C) where D) which
這邊要說在其他國家，米老鼠反映出美國的帝國主義及美國的價值觀。
空格前面是國家表地方，所以要選where，所以選C

3. ________ most of his time devoted to the extracurricular activities, Allen, one of the gifted students in my class, got only mediocre scores in his major studies.
A) When B) With C) Despite D) Although
前面只是個介系詞片語，並非完整的句子，所以連接詞都可以先省(A/D)，然後按照句意，C表示儘管，後面要接相反意思的句子，在此句意不合，所以選B。 (ALLEN是班上很有天分的孩子之一，他大部分的時間都在搞課外活動，結果最後成績平平。)

4. Finland is the least densely populated country on the continent and ________ its five million residents enjoy one of the highest standards of living anywhere.
A)alike B) then C) thus D) yet
這句也是依照句意來判斷，前面表示人口很少，後面說生活水準很高，自然表達的是轉折，所以選項中唯一能表達轉折的是D

5. _____________ for his diligence and persistence, the new deputy director is expected to bring up the office morale.
A) To know B) Knowing C) By knowing D) Known
這邊考分詞構句，前後主詞一樣，前面主詞可省。
原句可以寫成 The new deputy director is known for his diligence and persistence, the new deputy director is expected to bring up the office morale. 省掉前面一樣的主詞，就變成 is known for...，is要變成being known for...，being又可以省略，最後變成known for，所以選D

These questions have NOTHING to do with grammar, but just which word fits better in the context.