A:一定落在中央亮条纹上
B:一定落在亮条纹处
C:不可能落在暗条纹处
D:落在中央亮条纹处的可能性最大
分解因式:(a﹣4b)(a+b)+3ab.
A great number of students said they were forced to practise the piano.
下列属于变异现象的是()