题目

—There _______ a concert this evening.         —That’s great.         A. are going to be    B. is going to be  C. is going to have D. will have 答案：B图是一个长方形试管架，在a cm长的木条上钻了4个圆孔，每个孔的直径为2 cm，则x等于（   ）A．cmB．cmC．cmD．cm