[ANSWERED] 1. What documentation is required in order for a travel or entertainment expense to be deductib le?.

1. What documentation is required in order for a travel or
entertainment expense to be deductib le?
2. Under what circumstances can prepaid expenses be deducted
in the year of payment by a taxpayer using the cash method of accounting?
3. Under what circumstances would a taxpayer use both the
cash method and the accrual method of accounting at the same time?