Indicate clearly that they can choose to participate or not.

明确指出他们可以选择是否参加。

youdao

Feel free to quote from them, but indicate clearly when you are quoting.

可以引用资料，但是在引用的时候一定要清晰地注明出处。

youdao

Feel free to quote from them, but indicate clearly when you are quoting.

可以引用资料，但是在引用的时候一定要清晰地注明出处。

youdao