A:基因突变
B:染色体变异
C:自然杂交
D:自然选择
若向量a→=(1,1),b→=(2,5),c→=(3,)满足条件(8a→—b→)·c→=30,则x= ( )
Can you help me ____________ my homework?
Please ____________the light when you leave the room.