因为A×13=B×34,
则A:B=34÷13=34×3=9:4;
故答案为:9、4.
Mrs Smith lives next to us. She is really a good _______, because she always helps us.
A.visitor
B.waiter
C.neighbour
D.manager
滚动轴承径向工作间隙太小不会导致润滑油膜层破坏而发生轴承高温烧附。