在前三期(4月11日)里，谈到不可数名词是没有复数形式的，但是常常有人不小心，在某些不可数名词上加“-s”而犯错，其中“ experience, equipment, evidence, information”这几个的错误最多。

下面一家装修商广告中的“experiences”(经验)便是一例：

“……our many years of reputable experiences.”

须知，当“经验”解时，“experience”是不可数名词，不可以有“-s”：“……our many years of reputable experience(许多年声誉卓著的装修经验)”。当“各种各样不同经历”解时，“ experience”是可数名词，可以有复数“-s”的符号，如：

“Tom could not forget his thrilling experiences in his first trip to Guilin.”

学生作业中，类似的错误也不少，如：

① A lot of factors led to students’ poor performances. (应为 performance)

② Only people of irreproachable characters can aspire to be good leaders.(应为 character)

③ More and more institutions resort to advanced equipments to assist in the education process.(应为 equipment)

④ Without such knowledges, one would not be able to understand what was seen or heard. (应为 knowledge)

⑤ There is still much room for further improvements.(应为 improvement)

上述这些不可数名词的错误，是不是很熟悉呢?

刚刚谈的错误是不可有“-s”而用“-s”。另一种错误是应该有 “-s”而不用“-s”。虽然后者不像前者这样麻烦，但是也不难看到。下面三个不同的广告中便出现了应该有“-s”但漏了“-s”的名词：

⑥“We are looking for suitable candidate to take up the following positions.”(应为 candidates)。

⑦“Dear customer: Have you been misled by too many brochure?”(应为 brochures)。

⑧“We specialise in rubber tile for factory, office, warehouse, etc.”(应为 rubber tiles, factories, offices, warehouses)

⑥-⑧里的错误显而易见，只要稍微小心，便不难发现而改正过来。但是，有关不可数名词加“-s”的错误，则较难躲闪，必须加倍警惕才好。其中一个防患办法是借重量词，反映不可数名词之“量” ，但不改变其形，即不要用“-s”，如：

⑨ There isn’t much petroleum in the car.

⑩ John gave some evidence to indicate that the documents had been tampered with.

11. A little knowledge is a dangerous thing.

12. A lot of money has been donated to various charity organisations.

13. Some people today paid little attention to their extravagant acts.