题目

My name is Lucy and this is my grandfather. His name is Tim and he is my best friend. My grandfather is 64 years old and he is retired now, so he has much time to be and play with me. I love him very much and I know he loves me too. He lives with me, my father, my mother and my brother Kevin. We live in a big house. My grandfather is a very tall and strong man! Can you see me on his shoulders (肩膀) in this picture? He is really strong! My grandfather always knows what I want to do or to eat or what I feel inside! When I am sad, he makes me laugh with his funny faces. Every night before I go 匀强电场中有M、N、P三点，连成一个直角三角形，MN＝4 cm，MP＝5 cm，如图所示，把一个电量为－2×10－9 C的检验电荷从M点移到N点，电场做功8×10－9 J，从M点移到P点电场力做功也是8×10－9 J，求匀强电场的方向和大小．