1) He' s busy copying the letters.
他忙于缮写信件。
2) He was busily engaged in writing letters.
他正忙于写信。
3) He was busy with his writing.
他忙于写作。
4) We are engaged in writing a letter.
我们正忙于写信。
5) He was busily engaged writing letters.
他正忙於写信。
补充资料：我们
1.代词。称包括自己在内的若干人。
说明：补充资料仅用于学习参考，请勿用于其它任何用途。
参考词条