当open为形容词时,意为“开着的”,用于系动词后作表语.例如：The window is open.
当open为动词时,意为“打开”,在句中作谓语.例如：1）He opened the door and went out.
2）The room is very hot, he opens the window.
说明：opens是动词一般现在时的“三单”形式；opened是动词的一般过去式.
同上,close是动词,closed则是形容词.