Zhang Yan participated in this mathematics graduation exam, and used (1/6) of the total test time to complete the fill-in-the-blank and judgment questions, and (1/6) of the total time to complete the choice and calculation questions, and finally used ( 4/9) Completed the operation questions and problem solving (the total test time is at the beginning of the book). How long does she have to check?
张燕参加这次数学毕业考试，用了测试总时间的(1/6)完成填空和判断题，又用了总时间的(1/6)完成了选择和计算题，最后用总时间的(4/9)完成了操作题和解决问题(测试总时间在卷首)．她还有多长时间可用来检查？
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">1 - (1/6) - (1/6) - (4/9)</gadget>
<output>2/9 = around 0.222222</output>

<result>2/9 = around 0.222222</result>