Theodore will be able to file his tax return on time only in the event that he has an accountant prepare his tax return and the accountant does not ask Theodore for any additional documentation of his business expenses  If he does have an accountant prepare his return, the accountant will necessarily ask Theodore to provide this additional documentation
Ttherefore, Theodore will not be able to file on time
Susannah will have a relaxing vacation only if her children behave especially well and she does not start to suspect that they are planning some mischief. Since she will certainly start to suspect that they are planning some mischief if they behave especially well, Susannah's vacation cannot possibly be relaxing.