as a test; as an experiment; by way of experiment; by way of trial; tentatively
the proof of the pudding is in the eating; the proof is in the pudding; don't knock it till you've tried it; you can't tell unless you try
has never (done, occurred); there has never been an instance (where); there is no precedent (for)
the proof of the pudding is in the eating; the proof is in the pudding; don't knock it till you've tried it; you can't tell unless you try
online preview (of a book, magazine, etc.)
has never (done, occurred); there has never been an instance (where); there is no precedent (for)
introductory price (discounted); trial price