把……写在黑板上 write…on the blackboard
A：The teacher repeated the word, and then wrote it on the blackboard.
老师重复了一遍这个单词，然后把它写在了黑板上。
B：Did you learn the word by heart?
你记住这个单词了吗？
repeat /r??pi?t/ v. 重复；重做；复述
■ learn sth by heart 意为“记住某物”。例如：At school we had to learn a lot of poetry by heart.（在学校我们不得不记住很多诗歌。）
用湿抹布擦黑板 wipe the blackboard with a wet rag
A：You could wipe the blackboard with a wet rag.
你可以用湿抹布擦黑板。
B：I think I'd better not. I don't know if it's OK to erase this diagram.