题目

Do you wake up in the morning dreading the moment that your feet have to hit the floor for you to get ready for work? If that’s the case, join most of Americans. Very few people wake up to that annoying alarm clock and spring out of bed excited about having to go to work. As if that were not enough, most of us have to fight traffic getting there, usually an hour’s drive. Then, when we get to work, we have to fight with unruly co-workers or a nagging boss. And to make matters worse, you have to fight the same traffic going in the opposite direction just to get back home. Making dinner, fix 一块重为20牛的正方体木块浸没于水中，放手后木块上浮，请在下图中画出木块在上浮过程中所受重力G的图示．