题目

YBa2Cu8Ox(Y为元素钇)是磁悬浮列车中的重要超导材料，关于Y说法正确的是   A．钇在周期表中的位置是第4周期ⅢB族   B．属于非金属元素  C．质子数与中子数之差为50               D.Y和Y是两种不同的核素 答案：D阅读理解     Parents should help children understand money.   1   So you may start talking about money when your child shows an interest in buying things, candy or toys, for example.     1. The basic function of money     Begin explaining the basic function of money by showing how people trade money for goods or services. It's important to show your child how money is traded for the thing he wants to have. If he wants to have a toy, give him the money and let him hand the money to the cashier (收银员).    2  When your child grows a bit older and understands the basic function of money, you can start explaining more complex ways of using money.     2. Money lessons     Approach money lessons with openness and honesty.   3   If you must say no to a child's request to spend money, explain, "You have enough toy trucks for now." Or, if the request is for many differentthings, say, "You have to make a choice between this toy and that toy."     3.   4      Begin at the grocery store. Pick out two similar brands of a product - a name-brand butter and a generic (无商标产品), for example. You can show your child how to make choices between different brands of a product so that you can save money,   5   If he chooses the cheaper brand, allow him to make another purchase with the money saved. Later, you may explain how the more expensive choice leaves less money for other purchases.A. Wise decisionsB. The value of moneyC. Permit the child to choose between them.D. Tell your child why he can-or cannot-have certain things.E. Ask yourself what things that cost money are most important to you.F. Talk about how the money bought the thing after you leave the toy store.G. The best time to teach a child anything about money is when he shows an interest.