第一句話：
1.these three studies改成the three studies就好了
2.make significant contributions to后面的內(nèi)容不是很清晰.為什么做出了巨大貢獻(xiàn).僅僅說了an important fact是發(fā)現(xiàn)了一個fact呢,還是其他?不得而知.
3.leader我想這里你想要表達(dá)的是leadership,領(lǐng)導(dǎo)能力的意思.
4.companies后面不應(yīng)該用定語從句,其實幾個名詞,用作同位語就好了
修改后是這樣的：These three studies make significant contributions to the findings of an important factor of leadership large companies,especially group companies or multinational ones..
第二句：
1.make useful proposals讀起來怪怪的.好像沒有useful proposal這個表達(dá)法,useful suggestions更好.
修改之后是這樣的：They all make useful suggestions in addressing such issues as what makes a successful business leader or manager in the 21st century.
第三句：
1.compeitive advantage我才你是想表達(dá)競爭優(yōu)勢.其實competitiveness一個單詞就夠了.
2.recommend在這里好像不太合適.不是單詞不對,而是你好像沒推薦什么.
修改之后是這樣：It is suggested that further studies are important source of competitiveness for companies.