that sounds good? that 为什么是主语第三人称形式啊 ?求大师讲解一下

that sounds good? that 为什么是主语第三人称形式啊 ?求大师讲解一下 我想问你一下that sounds fun 为什么要加s?不是只有主语是第三人称单数是吗,这个也没有啊? that sounds fun 为什么sounds要加s,单三不是主语是第三人称单数时加s吗,为什么这个要加s? that sounds good 为什么不是that‘s sounds good ? 是That sounds good还是That's sounds good 是That sounds good.还是That's sounds good. That sounds good中的sounds为什么要加s That sounds good That sounds good. That sounds( )是good 还是well? sound是系动词吗?如果是的话,那为什么都说That sounds good!而不是That sounds well! that sounds good不是this sounds good