A．call on Monday B．ask the operator to pay some money C．keep waiting D．phone on a Sunday
单项选择题What is the most expensive type of call（）
A．Direct dial. B．Through the operator. C．Reverse charge call. D．Outside office hours.
单项选择题When is it cheaper to make an international call（）
A．10a.m. B．5p.m. C．11 p.m. D．11a.m.
