题目

三、阅读理解（共20小题；每小题2分，满分40分） 请阅读下列短文，从每题所给的四个选项（A、B、C和D）中，选出最佳选项，并在答题卡上将该选项的标号涂黑。 Going back to school is a very exciting event for my two boys. It means getting new school bags and books, and seeing friends again after the summer holiday. My oldest son, 9-year-old Salem, asked me several times where we would go to buy a backpack, while my other son, 6-year-old Abdullah, asked what school would be like this year. For the last three years, school was a nightmare说出下列多项式是几次几项式： (1)3x＋4y－5；(2)3ab＋2a－b；(3)3x2y－2＋3x2－6xy2．