为什么是look for it 而不是Look it for

look for it还是look it for look it for or look for it 为什么是 look for it 而不能是 look it for? 为什么说 look it up 而不说look it for 为什么说look it up 却说look for it can you help me look for it 为什么用for look for it 与look at it的区别.举例说明 为什么是it isn't good for you而不是it doesn't good for you 寻找她的钥匙为什么是look for her keys而不是find her key It looks good,为什么LOOK加S,这是我们自己看起来,而不是物体本身看 it's hard (to find) a job,为什么不能用to look for/to find out look for和look