要使SO2和SO3两种物质中含有相同质量的氧元素，则SO2与SO3的质量比为 。
6:5
y=x3-27x+2在[1，2]上的最大值为______．
The West Lake is famous for its beautiful scenery.
A．is bad for
B．is useful for
C．is good for
D．is well-known for
