Driving in Canada is similar to driving in many parts of the United States. Distances and speeds, however, are posted in kilometers per hour and some signs, particularly in Quebec, may only be in French.

    Unless otherwise posted, the maximum (最大限度的) speed limit in Canada is 50km/hr in cities and 80km/hr on highways. On rural highways, the posted speed limit may be 100km/hr. It is illegal to take automobile radar detectors (汽车雷达检测器) into Quebec, Ontario, Manitoba, and the Yukon. Seat belt use is required by law for all passengers, and child car seats must be used by children under 40 pounds. Some provinces require drivers to keep their vehicles' headlights on during the day and some have banned (禁止) driving while using a hand-held cell phone. Motorcycles cannot share a lane (车道), and safety helmets for motorcycle riders and passengers are necessary. Running a red light is a serious crime throughout Canada and drivers are advised to stop before starting when a light turns green.

    Winter travel can be dangerous due to heavy snowfalls and icy conditions. Some roads and bridges are often closed in winter. Snow tires are required in some provinces. Travelers should also be careful about animals while driving at night in rural areas.

    Highway 401, from Detroit to Montreal, is one of the busiest highways in North America. It has been the scene of many deadly traffic accidents due to sudden and severe weather changes, high rates of speed, and heavy truck traffic. Thus drivers should be alert while travelling here.

    Please refer to our Road Safety page for more information. Also, we suggest that you visit the website of Canada's national authority responsible for road safety.

板块构造学说认为地球表面是由____大板块构成，板块是在不断____的．一般来说，板块的内部地壳比较____，板块与板块交界的地带，地壳比较____，多____和____发生．

世界政治格局是指世界上主要政治力量通过一系列的抗衡、分化组合而形成的一种结构。这种结构在一定时期内处于相对稳定的状态，但又处在不断发展变化之中。阅读下列材料，回答问题。

材料一：列宁说：“靠《凡尔赛和约》来维持的整个国际体系、国际秩序是建立在火山口上的。”

材料二：对欧洲或北美一个或数个缔约国的武装进攻，应视为对缔约国全体之攻击。

材料三：冷战消失了……为具有更加多元化特点的社会开启了大门。

﹣﹣以上材料均摘自人教版《世界历史》九年级下册