Never before was travelling to foreign countries so convenient and popular as in this century. This phenomenon is partially attributed to improved technology and cheap flight tickets. （首句用一个倒装句引出题目背景，但是要注意，首句一定要稳妥，如果不确定写的对不对，不如朴实一点，保证没有语法错误。）Facing this travel frenzy（狂热 less common words）, some are concerned that it will bring about too many side effects whilst others insist that is should be supported and maintained.
Admittedly, cross-border travel has more downsides than one. Firstly, the carbon dioxide planes emitted is reported to be disproportionately（注意副词的使用） more than that emitted by other transportation means. The carbon dioxide will lead to ozone layer thinning（臭氧层变薄） and thereby increasing the probability of people contracting skin cancer(患皮肤癌的几率). Moreover, being easier and more convenient to travel among countries means that some criminals could flee to other countries after committing hideous crimes（罪大恶极）. This will pose a threat to （造成威胁）local security and community stability.
However, the downsides cannot overshadow its upsides. For starters, travelling around the world with more ease could expand individuals’ horizons and stimulate their love of life and they will be more productive at work in the future. Moreover, companies could visit foreign markets more conveniently than before and as a result, they could locate potential target market and sell goods there or buy materials from there if the price is competitive enough. If a company could flourish this way, employees will benefit and the society in which companies are operating will be more stable and harmonious. Last but not least, if more and more people are afforded opportunities to go to other countries, there will be less misunderstanding and more respect among countries. All these will contribute to a diverse but harmonious culture.
To sum up, despite the numerous drawbacks mentioned above, travelling to other countries with more convenience and ease is, by and large,（注意高级句式-插入语的使用） a positive development.