【问】 (1)Although Campbell reached a speed of over 304 miles per hour，he had great difficultyin controlling the car because a tyre burst during the first run. (New Concept English，Book 2，L.72)
 (2) Since that time，racing drivers have reached speeds of over 400 miles an hour.(NewConce pt English，Book 2，L.72)
 (3) By working at tremendous speed，the men managed to get the dish on to dry land be-fore the wave returned. (New Concept English，Book 3，L.43)
 请问上面的speed，a speed，speeds哪一个是正确的?
 【答】 这是英语教学中学生们经常提出的一个问题，而我们做英语教师的由于手头缺少这方面的资料，常常回答不好。我们应当明确地告诉学生上面的用法都是正确的，而且在语义上毫无区别，这就是说，speed既可以用作不可数名词，也可以用作可数名词。例如：
 1. I drive at great speed to West Bank. (EED)
 我快速开车到西部银行去。
 2. It moved with great speed. (Palmer)
 它以极高的速度运行。
 3. The train was travelling at ordinary speed. (Palmer)
 火车以正常的速度运行。
 4. ...capable of reaching speeds of over 110 kph. (EED)
 ……能达到每小时110多公里的速度。
 5. We were travelling at a speed of thirtymiles an hour. (Palmer)
 我们正在以每小时30英里的速度行驶。
 6. “I think John will win the race. ”
 “Yes，he started off____a great speed. ”
 A. with B. at C. through D. by(TOEFL，71.1)
 但是，当speed作“快速”、“迅速”解时，则总是用作不可数名词：
 1. It’s dangerous to corner at speed. (ALD)
 高速转弯是很危险的。
 2. The car is travelling at speed. (EED)
 汽车正在高速行驶。
 3. More haste less speed.
 欲速则不达。