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The rationale for this is that such packages tend to embed additional information in the file, e.g. to specify the size and style of fonts in use, etc. This additional information will not generally be preserved in the email system, and may actually render the report unreadable at the receiving end.

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Asking a colleague or demonstrator will not generally apply in a Lab exam of course; but even in that case you may ask for certain kinds of help - e.g. if you think the instructions you have been given are inconsistent or impossible to carry out.