the only answer i can give at present is to wait a few more years, at which time something better might ultimately come out of all our efforts.
i think it will be possible to answer this question when more experiments are completed.
the answer to this question needs further study.
i hope i will be able to answer your question later.
i appreciate your interest in my research, but i just don't want to talk about it now. let's talk about something else.
i'd rather not say.
why do you want to know?
sometimes you can relay the question back to the questioner. for example,
before i answer you that question, let me ask you: where do you think we should have the project?