Matrix with multiple choices (type:'matrixdropdown')

Source code: Survey setup
Survey.defaultBootstrapCss.navigationButton = "btn btn-primary";
Survey.Survey.cssType = "bootstrap";
var survey = new Survey.Model({questions: [
{ type: "matrixdropdown", name: "frameworksRate", title: "Please tells us your opinion about JavaScript MVVM frameworks",
    choices: ["Excelent", "Good", "Average", "Fair", "Poor"],
    columns: [{ name: "using", title: "Do you use it?", choices: ["Yes", "No"], cellType: "radiogroup" }, 
              { name: "experience", title: "How long do you use it?", choices: [{value: 5, text:"3-5 years"}, {value: 2, text:"1-2 years"}, {value: 1, text:"less then a year"}] }, 
              { name: "strength", title: "What is main strength?", choices: ["Easy", "Compact", "Fast", "Powerfull"], cellType: "checkbox" }, 
              { name: "knowledge", title: "Please describe your experience", cellType:"text" },
              { name: "rate", title: "Please rate the framework itself" }],
    rows: [{ value: "angularv1", text: "angularjs v1.x" }, 
           { value: "angularv2", text: "angularjs v2" },
           { value: "knockoutjs" }, 
           { value: "reactjs"}]}
]});

$("#surveyElement").Survey({model:survey});