关闭文件错误的I / O操作

因此，我正在编写此程序，该程序使用open（）创建读取文件。当我尝试运行该程序时，出现以下错误：ValueError：关闭文件上的I / O操作（第18行）。

在有关该主题的每个问题中，问题始终与缩进有关。IE试图对未在同一循环中打开的文件进行操作。我对python有点生疏，但缩进对我来说似乎还不错。

我希望有人可以快速浏览一下，让我知道缩进是否错误，或者是否有其他原因导致该错误？代码（注释错误）：

sourceFile = 'test.html'
serviceTarget = "Plumbers & HVAC Experts"
cityTarget = "NJ"

services = {"Plumbers", "Air Conditioning Experts", "Drain Cleaning Experts"}
cities = {"Westfield", "Scotch Plains", "Clark"}

serviceNames = {"Plumbers":"plumbers", "Air Conditioning Experts":"ac", "Drain Cleaning Experts":"drain"}
totalPages = len(services)*len(cities)

for serviceRep in services:
    for cityRep in cities:
        outFileName = cityRep + " " + serviceNames[serviceRep] + ".html"
        outFileName = outFileName.replace(" ", "_");
        print("Writing " + outFileName + "...")
        infile = open(sourceFile)
        outfile = open(outFileName, 'w')
        for line in infile:   #This is the line giving me problems
            if serviceTarget in line:
                line = line.replace(serviceTarget,serviceRep)
            if cityTarget in line:
                line = line.replace(cityTarget,cityRep)
            outfile.write(line)
            infile.close()
            outfile.close()
        totalPages -= 1; 
        print("DONE -- " + str(totalPages) + " left to go")