,则其中x的一次项的系数为( )\n \n \n \n \n \n \n \n \n \n \n A.\n 1\n
\n \n\n \n \n \n B.\n -1\n
\n \n\n \n \n \n C.\n 2\n
\n \n\n \n \n \n D.\n -2\n