1. 單選框的值

<div class="ques_one">
    <p>1. 一個月健身幾次最好？（單選）</p>
    <ul>
        <li>
            <label>
                <input type="radio" name="question1" value="A" />
                <span>A 一月八次</span>
            </label>
        </li>
 

        <li>
            <label>
                <input type="radio" name="question1" value="B" />
                <span>B 一月七次</span>
            </label>
        </li>
        <li>
            <label>
                <input type="radio" name="question1"
 
 value="C" />
                <span>C 一月十次</span>
            </label>
        </li>
        <li>
            <label>
                <input type="radio" name="question1" value="D" />
                <span>D 一月十二次</span>
            </label>
        </li
 
>
    </ul>
</div>
<div class="submit_btn">
    <input type="button" class="btn" value="提 交" name="dosubmit" onclick="questionsubmit()" />
</div>
<script>
    function questionsubmit(){
        var qs1 = $("input:radio[name='question1']:checked").val();
        if(!qs1){
            alert("請填寫第1題的答案");
            return false;
        }   
    }
</script>

1. 複選框的值

<div class="ques_one">
    <p>3. 以下說法正確是？（多選）</p>
    <ul>
        <li>
            <label>
                <input type="checkbox" name="question3" value="A" />
                <span>A 一個周健身2次</span>
            </label>
        </li>
        <li>
            <label>
                <input type="checkbox" name="question3" value="B" />
                <span>B 一個周健身3次</span>
            </label>
        </li>
        <li>
            <label>
                <input type="checkbox" name="question3" value="C" />
                <span>C 一個周健身4次</span>
            </label>
        </li>
        <li>
            <label>
                <input type="checkbox" name="question3" value="D" />
                <span>D 一個周健身5次</span>
            </label>
        </li>
    </ul>
</div>
<div class="submit_btn">
    <input type="button" class="btn" value="提 交" name="dosubmit" onclick="questionsubmit()" />
</div>
<script>
    function questionsubmit(){
        var qs3='';
        var q3 = $("input[name='question3']:checked").each(function()
        {
            var result = this.value;
            if(result){
                qs3 += result;
            }
        });
        if(!qs3){
            alert("請填寫第3題的答案");
            return false;
        }
    }
</script>