广泛（extensive）学习／研究和集中（intensive）学习／研究之间，有什么差别？为此，我查阅了四本字典：Merriam-Webster Unabridged（第3版）、The New Shorter Oxford English Dictionary、Webster’s New World College Dictionary（第4版），以及The American Heritage Dictionary（第5版）。
- Intensive＝深刻的；高度集中；彻底；详尽的
- Extensive＝范围或数量大；深远；全面；宽广
就以上定义，我们可以看到：于某些定义，这两个词像是反义词（如高度集中的、广泛的）；而在其他定义上，它们更像是同义词（如详尽的、全面的）。这也就无外乎一些英语非母语的作者，在使用这两个词时，常感到困惑。
我建议，当描述针对特定议题而进行的深度研究时，应使用intensive或intensively；相反地，就某议题的各种侧面，而进行广泛的研究，则应使用extensive或extensively。
以下例举intensive、intensively、extensive和extensively的一些惯常用法：
At an intensively studied site within the region, >90% of the dominant overstory tree species died after 15 months of depleted soil water content.
The figure illustrates a typical spine synapse that makes intimate contact with an apical dendrite of a pyramidal cell. The ultrastructure of such synapses has been intensively studied in our laboratory.
Plasma membrane transporters have been intensively studied at the mechanistic, biochemical, and molecular levels.
The asymmetric aldol condensation has been the subject of intensive study in our laboratory.
The asymmetric aldol condensation is among the most powerful reactions in synthetic organic chemistry and has been extensively studied over the past 15 years.
As surrogates for the central nervous system, peripheral samples such as blood, saliva, and skin have been extensively used in psychiatric research for decades.
Because of its importance in cholesterol biosynthesis, HMG-CoA reductase has been extensively studied.
另外，这两个词可以并列出现在同一个句子中吗？我在Google Scholar搜索中发现以下句子：
One-dimensional ZnO nanostructures have been studied intensively and extensively over the last decade not only for their remarkable chemical and physical properties, but also for their current and future diverse technological applications.
我不确定该怎么看待这句话。您觉得呢？
使用Concerning一词
当您向科学期刊投稿时，您希望编辑与审稿人关注您的研究而非写作，因此您的写作应该在不引人注目的情况下，传达您的意思。当然，正确的文法、标点符号与拼法很重要，但您的写作对母语人士来说也必须读起来很自然才行。实现此目的的一个方法是避免单词使用中的细微错误。
我在教授ESL写作课上，常遇到学生将concerning作形容词用，如：
原句一：There was a concerning trend toward long-term late deterioration in the laminectomy-alone group.
尽管有些辞典确实赋予concerning形容词的词性，具“给予关注的”含义，如giving concern（Merriam Webster’s Unabridged ），但将a concerning trend 一词输入网络搜索，只有大约五百个搜索结果（非常低），可见大家很少这样用。鉴于此，我建议将以上原句一，做如下修改：
改句一：There was a disturbing trend toward long-term late deterioration in the laminectomy-alone group.
改句二：In the laminectomy-alone group, there was a trend toward long-term late deterioration, which is a cause for concern.
更多范例如下：
原句二：We observed a concerning trend toward a higher incidence of postoperative bleeding in patients who received clopidogrel within 5 days of undergoing coronary artery bypass grafting.
改句：We observed a worrisome trend toward a higher incidence of postoperative bleeding in patients who received clopidogrel within 5 days of undergoing coronary artery bypass grafting.
原句三：Although we have not yet seen this phenomenon with ZD1839, this is still a concerning result that will require additional study.
改句：Although we have not yet seen this phenomenon with ZD1839, this alarming result will require additional study.
原句四：This concerning state of affairs led to a surge in research activities to discover and develop new antibiotics to combat the increasing threat of bacterial resistance.
改句：Concern about this state of affairs led to a surge in research activities to discover and develop new antibiotics to combat the increasing threat of bacterial resistance.
总而言之，为避免语意歧义以及更符合英语的使用习惯，请尽量将concerning视作介词使用，代表in reference to或about的含义，例如：
Controversy concerning the mechanism of cell-penetrating peptides has recently arisen。
