be busy 什么 on还是of还是for还是with

be busy 什么 on还是of还是for还是with be busy+in还是on还是at还是不加 BE busy with 还是 BE busy to be busy加什么?be busy是接doing sth还是to do sth? be busy doing还是be busy to dokuai be busy to do 还是 be busy doing be busy with study还是be busy at study be busy with与be busy at的区别是什么? be find of doing还是be find on doing he is always busy___ (work)是用be busy doing sth还是 be busy with sth 是be busy doing sth还是be busy to do sth? 存不存在be busy on the teacher gave me a piece of paper to write on,还是to be written on? 是be focus on 还是focus on focus on还是be focus on be busy 加什么 The knots of your package must be tied tightly.应该是of还是on? be busy doing sth 中的busying是动名词还是现在分词,这里面得busy是形容词还是动词? 是on the fourth of february还是什么