化简：$\sqrt{8}\times \left(\sqrt{2}+\sqrt{\frac{1}{2}}\right)$．

下列根式中，不是最简二次根式的是(   )

下列各项中，哪一项疾病可能是由于不良生活习惯造成的（   ）

根据短文内容选择正确答案。

    Traveling is one of the most important things and people have been interested in it for many years. Modern traffic develops(发展) fast. So traveling to different places has become much easier than before.

    Staying healthy while traveling can make your trip happier. But do you know how to keep healthy during a trip? The following information may be useful for you.

    Before traveling:

    Wear comfortable shoes, a hat and sunglasses.

Take some necessary medicine with you. They can be used when you get sick or have other problems.

If you do lots of sports like walking or climbing during your trip, you should do some exercise for weeks or months before you leave.

    While traveling:

    Be sure not to eat dirty food or bad fruit.

    Have enough time to take a rest during your trip.

    Tap water is not safe, so drink bottled water and always clean the cover of the bottle.

明代《织工对》记载：“余僦居钱塘之相安里，有饶于财者，率聚工以织。……进而问之……工对曰：吾业虽贱，日佣为钱二百缗，吾衣食于主人，而以日之所入，养吾父母妻子，虽食无甘美，而亦不甚饥寒。”材料表明在明代（  ）