A: I have an assignment on world water reservation. I have no idea of it.
B: Why not go to the library?
A: It has been closed now, but I have to hand it in tomorrow.
B: Don't worry. I have some books to the purpose. It may be helpful to you.
to the purpose
exp. To the point; that which is pertinent. （切中要害地，中肯地，切题地）
e.g. We don't have much time left, so please, get to the purpose.
e.g. What he had said was not to the purpose.
e.g. His remarks about gardening were hardly to the purpose.
e.g. She often speaks to the purpose.
1. have no idea of something：不知道……
e.g. That' s a difficult question and I have no idea of the answer.
e.g. These creatures never suspect and they have no idea of a sarcasm.
e.g. That June would have trouble with the fellow was as plain as a pikestaff——he had no more idea of money than a cow.
2. hand in：上交
e.g. I do not know when she can hand in her school assignment.
e.g. We should give them notice to hand in the applications before Friday.
3. be helpful to：对……有帮助
e.g. He's always very helpful to his mother.
e.g. All this comes down to one point: work is helpful to health.
其它：have an assignment：有作业 an assignment on：关于什么内容的作业