IT测验 - 除非选中复选框，否则不显示答案

Question

我正在尝试确保至少选中了两个复选框。如果未选中任何复选框，则会显示错误消息。这是我到目前为止所尝试的：

function quiz4() {
var a4 = document.getElementsByName('q4');
    for (i = 0; i < a4.length; i++) {
        if(a4[i].checked == false) {
            document.getElementById('oCorrectAnswer4').innerHTML = "Please select your answers.";
        }
    }

    if (document.getElementById('q41').checked && document.getElementById('q43').checked) {
        document.getElementById('oCorrectAnswer4').innerHTML = "Correct: The answer is " + "<u>A) Keyboard and C) Finger Print Scanner</ul>";
        inputs = document.getElementsByName('q4');
            for(var i = 0; i < inputs.length; i++) {
                if(inputs[i].type == 'checkbox') {
                    inputs[i].disabled = true;
                }//end of if
            }//end of for
    } else {
        document.getElementById('oCorrectAnswer4').innerHTML = "Incorrect: The answer is " + "<u>A) Keyboard and C) Finger Print Scanner</ul>";
        inputs = document.getElementsByName('q4');
            for(var i = 0; i < inputs.length; i++) {
                if(inputs[i].type == 'checkbox') {
                    inputs[i].disabled = true;
                }//end of if
            }//end of for
        }
}//end of q4

我知道这不起作用，因为for循环被绕过（我猜），但我不得不从某个地方开始。

任何帮助将不胜感激。