【问】 我从初学英语时起就已牢记difficulty是个不可数名词，但是现在我却经常遇到a diffi-culty和difficulties这些形式。例如：Here is a difficulty for you to get over. It gets me in-to all kinds of difficulties.这是怎么回事呢?
 【答】 记得我国一位著名数学家说过：学知识的过程，不仅是一个学习新概念的过程，而且也是一个修正错误概念的过程。你对difficulty的了解，是有片面性的，应予修正。
 A.当difficulty表示抽象的“困难”、“费力”时，它是一个不可数名词。它既不能与不定冠词连用，也不能以复数形式出现：
 1. She spoke with difficulty. (EED)
 她说话很困难。
 2. I don’t have much difficulty with English Grammar.(Eckersley)
 我在英语语法方面没有多大困难。
 3. I was having difficulty breathing...(EED)
 我呼吸困难。
 4. With great difficulty，he climbed into the shop window to get the dress. (New ConceptEnglish，Book 2，L. 57)
 他费了好大劲爬上橱窗取那件衣服。
 5. We have difficulty in finishing the job in two days.
 我们在两天之内来完成这件工作，是有困难的。
 6. She’s not had much difficulty. (CGEL)
 她没有多大困难。
 B.当difficulty用于指具体的困难、难处、难点时，它是一个可数名词，既可以与不定冠词连用，也可以以复数形式出现：
 1. He paused as though he found a difficulty.(Wells)
 他停了下来，似乎发现了一个难点。
 2. The book is full of difficulties. (ALD)
 这本书充满了难点。
 3. She’s had many difficulties. (CGEL)
 她有许多困难。