丰胸有害:that is a green pen表语和宾语是否都是pen，其中that是主语？(详细)

that is a green pen表语和宾语是否都是pen，其中that是主语？(详细) that is a pen Is that a pen?Is that a pencil?(合并为一个选择问句) Dortors say that green tea is very good for you. That is a way it is He is now in the pen.He regretted having done that. That is a ___ idea.(填空） _____is the pen? It's green. This is a heads up that it is coming.中文？ There is the pen as I last time.中为什么用as而不用that或wich?