C# .NET使用vs代码构建多个项目

我正在尝试设置VisualStudio代码，以便在运行时构建多个dotnet项目

My task.json：

{
    "version": "0.1.0",
    "command": "dotnet",
    "isShellCommand": true,
    "args": [],
    "tasks": [
        {
            "taskName": "build_task",
            "suppressTaskName": true,
            "args": [
                "build", "${workspaceRoot}/main/project.json", "-o", "${workspaceRoot}/obj/", "--framework", "netcoreapp1.1"
            ],
            "isBuildCommand": true,
            "problemMatcher": "$msCompile"
        }
    ]
}

这很有效。但当我补充这一点时：

{
    "version": "0.1.0",
    "command": "dotnet",
    "isShellCommand": true,
    "args": [],
    "tasks": [
        {
            "taskName": "build_task",
            "suppressTaskName": true,
            "args": [
                "build", 
                "-o", "${workspaceRoot}/obj/",
                "${workspaceRoot}/main/project.json", "-f", "netcoreapp1.1",
                "${workspaceRoot}/pluginSample/project.json", "-f", "netstandard1.6"
            ],
            "isBuildCommand": true,
            "problemMatcher": "$msCompile"
        }
    ]
}

我得到这个错误：

Unexpected value 'netstandard1.6' for option 'framework'

但当我手动编译它时，它可以工作：

dotnet build -f netstandard1.6