单项选择题
A．difficult B．boring C．heavy D．appealing
A．he had to put his name on a waiting list B．he wrote the postmaster a note of appreciation C．many people had applied for post-office boxes before him D．he asked the postmaster to make one for him
A．anyone without breakfast does improve his performance B．not giving people breakfast improves performance C．people having breakfast do improve their performance D．having breakfast does not improve performance, either