如图所示，重为G的物体静止在倾角为α的粗糙斜面体上，现使斜面体向右做匀速直线运动，通过的位移为x，物体相对斜面体一直保持静止，则在这个过程中（   ）

    My parents moved to Mississippi when my brother and I were small children, and we were separated from our Oklahoma grandparents by some 600 miles. This long distance allowed us to only visit our grandparents once a year, either at Christmas or during summer vacation.

    Most of my classmates lived near their grandparents, and I would often hear stories of big families regularly spending time with one another, fishing at “grandpa's” house or going over to “grandma's”for her famous fried chicken. We were disappointed that we did not get to spend more time with our grandparents, but our love for them remained deep and strong.

    We always expected a road trip to Oklahoma. We would count the days, and when the day came, the entire family would pile into our car at four o'clock in the morning. Crossing the Mississippi River into Louisiana, the scenery changed. Crossing the Red River in Oklahoma, we were in a foreign world.

    Every trip to see my grandparents can't be without bringing delight. We jumped out of the car in their driveway to be met with bear hugs. My grandparents wanted to know everything about their grandchildren, and we would sit for hours and tell story after story. Grandma had a meal planned, and you could guess she prepared her grandsons' favorite foods. Of course the best part of the visit was that we were able to do whatever we wanted without punishment from our grandparents. Grandma and Grandpa always had presents for us, short trips planned and lovely surprises, such as the time we got to a local restaurant and ate the world's largest hamburger.

①古老的威尼斯又沉沉地入睡了。____

②两边的建筑物飞一般地往后倒退。____

③威尼斯的小艇行动轻快灵活，仿佛田沟里的水蛇。____

河宽420m，船在静水中速度为4m/s，水流速度是3m/s，则船过河的时间可能是（   ）