根据材料内容，选择正确答案。

Dear Frank,    

    Thank you for your postcard. I'm very glad you are having a good trip now. Ottawa is very beautiful in May. I hope I will have a chance to go there one day.

    Our summer holidays will start next month. I enjoy my summer holidays, although(虽然)it's hot at that time in America. During summer holidays，I can swim in the sea and go fishing. It's so cool. And I am going to our hometown near Chicago with my sister Linda，and my parents agree(同意). Our uncle lives  there，so Linda and I can stay with him.

    We are not going to take a plane. We are going there by train. I am going to fish there. And Linda likes painting. She is going to do some painting there. I'm sure we'll have a good time.

                                                            Sincerely,

                                                              Jack

2002个203相乘，积的个位是（　　）

下列关于物态变化说法正确的是（）

 材料：我国第四套人民币中的一元硬币是钢芯镀镍（Ni），镍与稀硫酸能发生下列反应：Ni+H₂SO₄═NiSO₄+H₂↑． 根据此材料及金属活动性顺序，请回答：

（1）铸造硬币用到的材料是____（填“合成材料”或“金属材料”）；

（2）写出Ni与CuSO₄溶液发生置换反应的方程式____ ．