a man can not smile like a child,（ ）a child smiles with his eyes ,while a man smile with his l

填 for因为的意思 a man can not smile like a child, for a child smiles with his eyes ,while a man smile with his lips alone大人无法像小孩那样笑, 因为小孩笑的时候,眼睛也会笑. 而大人笑的时候,就只是用嘴...and but so for as or这些连词一般什么时候用，解释什么？and 一般就表示并列...什么和什么比如 My father and mother will go to work.我爸爸(和)妈妈要去上班了. but一般表示转折 但是....I am a boy but you are girl. 我是个男孩,(但是) 你是个女孩. so 所以表示结果I love you so I wanna be with you 我爱你所以我想跟你在一起 as一般放句首, 做因为讲As I am busy now, I can't play with you, (因为)我现在很忙,没办法和你玩. or 或者一般用在选择疑问句 Which bag do you prefer, the black one or the red one?你喜欢哪个包多一点呢, 黑色的还是红色的?