opened是什么意思

this serial port already opened是什么意思 请问the door opened suddenly 这个opened后面的ed是什么意思?怎么来的? He opened the door to the balcony是什么意思 The cage holding Robo-man opened.这里的hold（holding）是什么意思? opened,open,close, The door opened and() I never opened my the shop is opened. S(),the door opened the store opened语法 who did opened the door who opened the door They opened their presents under the christmas tree.就opened