题干

如图,一个家用台灯静止放在桌子上,下列描述中正确的是(   )

A:台灯对桌子的作用力和桌子对台灯的作用力是一对平衡力

B:台灯受到向左的摩擦力

C:各旋转点O对灯头的作用力沿AB方向

D:台灯底座所受合外力为零

上一题 下一题 0.0难度 选择题 更新时间:2011-12-02 11:58:44

答案(点此获取答案解析)

D

同类题1

通读下面短文, 掌握其大意, 然后在每小题所给的四个选项中, 选出一个最佳答案, 并将答题卡上对应的选项涂黑。

    My parents are busy with their work every day. You can't see there is love 1 them. They don't act in the romantic(浪漫的)2that I read in books or I see on TV.

    One day, while Mom was sewing(缝) a quilt,I 3 beside her. “Mom, I have a question,” I said after a while.

    “What?” she asked.

    “Is there love between you and Dad?” I asked her in a very low voice.

    She stopped sewing and 4 her head. Then she bowed her head and went on sewing.

    I thought I had hurt her. At last I heard my mother say, “Susan, look at this thread(线). Sometimes it appears, but most of it disappears in the quilt. It makes the quilt5. If life is a quilt, then love should be a thread. It can hardly be seen, but it's 6 there.”

    I couldn't understand her 7 the next spring. My father suddenly got sick. Mom had to stay with him in the hospital for a month.

    After they 8, my mother helped my father walk slowly down the country road every day. My father had never been so gentle.

    “Dad, how are you 9 now?” I asked him one day. “Susan, don't worry about me,” he said. “I just like walking with your Mom.”

     Once I thought 10 meant flowers, gifts and sweet kisses. But from this experience, I understand that it is just a thread in the quilt of our life . It is inside, making life strong and warm.