on the blackboard的用法和樣例：
例句
- The boy stole from classroom while the teacher was writing on the blackboard.
老師在往黑板上寫字時，那孩子偷偷溜出了教室。 - He took out a piece of chalk and wrote his problem on the blackboard.
他拿出了一支粉筆並在黑板上寫下他的問題。 - The teacher wrote down the new words on the blackboard.
老師在黑板上寫出新單詞。 - The teacher wrote on the blackboard with a piece of chalk.
老師用一支粉筆在黑板上寫字。
