The only 'passengers' are occasional herds of specially recruited crowds, used for testing purposes.
Times, Sunday Times
Clinical microarray applications are further limited by the availability of sufficient cell numbers for testing purposes.
The Scientist
We have a mobile [phone] that we use for testing purposes.
Times, Sunday Times
A few will be retained for testing purposes and when storage space runs out, the others will be destroyed.
Times, Sunday Times
None of the games are entirely free but all offer a limited trial for testing purposes.
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