备受宁波市民关注的象山港跨海大桥在2012年12月29日建成通车，此项目总投资约77亿元，77亿元用科学记数法表示为（  ）

    There was once a guy who suffered from a cancer, one that can't be cured. He was 18 years old and he could die anytime. All his life, he____(stick) in his house taken care of by his mother.  He never went outside but he was tired____staying at home and wanted to go out for once. So he asked his mother and she gave him____(permit)

    He walked down his block and____(find) a lot of stores. He passed a CD store and looked through____front door for a second. He stopped and saw a beautiful girl about his age. He opened the door and walked in, not looking at anything else but her.

    He walked____(close) until he was finally at the front desk____she sat. She looked up and smiled, “Can I help you?” He said, “I would like to buy a CD.” He picked one out and gave her the money for it. “Would you like me to wrap it for you?” She asked____(smile) again. He nodded and she went to the back. She came back with the wrapped CD and gave it to him. After that, he often bought a CD there. One day, he went there buying a CD____he did every day, and once again she went to the back of the store came back with it____wrap). He took it and when she wasn't looking, he left his phone number on the desk and ran out…

水平桌面上放置一底面积为100cm²，重为6N的柱形容器，容器内装有20cm深的某液体．将一体积为400cm³的物体A悬挂在弹簧测力计上，弹簧测力计示数为10N，让物体从液面上方逐渐浸入直到浸没在液体中（如图），弹簧测力计示数变为5.2N．（柱形容器的厚度忽略不计，筒内液体没有溢出，物体未接触容器底．g=10N/kg），求：

（1）物体浸没在液体中时受到的浮力；

（2）筒内液体密度；

（3）物体浸没时，容器对桌面的压强．