2+____＝9        ____+6＝ 6 

____－3 ＝5        ____+____＝7

近年来，腾讯公司推出的为智能手机提供即时通迅服务的应用程序—微信，因其有不受时间、空间束缚、成本低等特点，深受用户欢迎，微信正在改变我们的生活。这说明（  ）

家庭电路的电压是____ V，对人体的安全电压是不高于____ V．电路中的电视机、电冰箱、电脑等用电器之间的连接方式是____ 联．影响导体电阻大小的因素有____ 、____ 、____ 和____ ．

      Traveling has been popular with people for a long time. Many of today's travelers are trying to find an unusual experience or adventure. Hiking may be a good choice.
       Instead of spending your vacation on a bus, in a hotel or sitting on the beach, you may want to try hiking. Hiking is a great way to travel. You will get close to nature and take exercise at the same time. Hiking is easy to do and doesn’t have to be very expensive. The basic equipments (设备) you need for hiking are simple: good shoes, clothes and a backpack. You can hike in the mountains, in a forest or along a river. You can also go for a hike in the city.
       Hiking is fun and exciting, but you shouldn't forget safety. Here are some basic tips for successful hiking:
      Don't hike alone.
      Bring water, a good map and a mobile phone.
      Wear a hat to protect yourself from the sun.
Answer the questions according to the passage.