找出下列句子的一處 語法錯誤：
When smart traffic lights are set up and traffic management softwares are installed, the number of green lights on each street has been optimized to avoid traffic congestion as well as to allow ambulances to reach incidents without any delay.
♜ 適用考題：
The most important problem affecting our society today will be solved in our lifetime. (2012.10.27)
答案：
When smart traffic lights are set up and traffic management software is installed, the number of green lights on each street has been optimized to avoid traffic congestion as well as to allow ambulances to reach incidents without any delay.
* software (不可數(shù)名詞)軟件;托福寫作常用不可數(shù)名詞，還有：education, transportation, equipment, evidence, globalization, feedback, homework, advice, information等。