Since then, researchers in the United States and Pakistan developed the helpline. Almost 300,000 people have called the service with questions about the symptoms of dengue. __________________________.
从那时起，美国和巴基斯坦的研究员研制出了热线服务电话。几乎有30万人打电话询问登革热的症状。________________________。
Experts say the system is not costly3. They say that in 2013 the number of dengue cases in the city of Lahore fell to 1,600 using information from the helpline and disease prevention efforts.
专家称，这项程序并不昂贵。他们称，2013年拉合尔的登革热病例下降到1600例，原因在于热线服务电话提供的信息，疾病预防做出的努力。
