读一读，写一写
①— Are there any ____ ?
— Yes, there are.
②There are many tall ____ in my city.
③There is a ____ above the river.
④- Are there any houses in the ____?
-Yes, there are.
下列关于磁感线的说法中正确的是（ ）
任意抛掷一枚硬币两次，至少有一次正面朝上的概率是（ ）
