题目

用数学归纳法证明13+23+33+…+n3=n2（++）. 答案：证明：（1）当n=1时，左=1=1·（++）=右，等式成立.（2）假设n=k时等式成立即：13+23+33+…+k3=k2（++），则n=k+1时，13+23+33+…+（k+1）3=k2（++）+（k+1）3=k2+（k+1）3=（k+1）2（+k+1）=（k+1）2［++］.∴当n=k+1时，等式成立.由（1）（2）知原等式对任意正整数都成立.Millie wants to know more about‘get’. Pick out the right word in the following  sentences which can replace "get", then put the word in the blank.  Eg. When did you arrive there?  arrive       He has learned 10 poems by heart since this morning.