这四张图的R代码怎么写

![img](https://img-mid.csdnimg.cn/release/static/image/mid/ask/831615126966140.jpg "#left"
请教各位，如何使用数据mpg，写出这四幅图片的代码，希望各路帮帮忙，十分感谢！

代码如下：

library(ggplot2)
a <- mpg
ggplot(data = a,aes(x=displ,y=hwy))+
  geom_point()+
  geom_smooth(method = 'loess',se = F)

ggplot(data = a,aes(x=displ,y=hwy))+
  geom_point()+
  geom_smooth(method = 'loess',se = F,aes(group=drv))

ggplot(data = a,aes(x=displ,y=hwy,color=drv))+
  geom_point()+
  geom_smooth(method = 'loess',se = F)

ggplot(data = a,aes(x=displ,y=hwy))+
  geom_point(aes(color=drv))+
  geom_smooth(method = 'loess',se = F)