study是学习的意思是是不可数名词,因此无复数.
education是不可数名词,因此后面动词也用单数.而且than后头要有比较的对象,改后为：
They think that education in other countries is better than that in their own country.
bring about是导致,引起,我认为光是bring就可以表达你的意思.具体的可以查查字典.
Next, studying abroad can cultivate students' ability to live independently and their characters.这句话的培养个性后面没有体现.
influence作动词时是否用on我不是很肯定,最好再查查字典.
not only……but also,改为：
They can not only master a foreign language and widen their horizons, but also cultivate their independence, which is the most important aspect of studying abroad.
总体评价:
文章结构很好,但是detail不够,很多论证不够不能充足证明support.词语句式可能过于简单了.