Limitations可以从几方面考虑: 资料方面,你所阐述的观点是based on a small sample 因而,你阐述的观点may have limited 同样,所用的资料可能偏重男性或老年人,所以,你的观点may be generalizable only to males or the 方法方面。Future Directions 就写你打算如何处理/解决前面提及的局限性。给你一个例句。The results of the study highlight the need for future research to use a more representative sample