单项选择题A．He didn’’t know that she was enrolled in a linear algebra course.B．He thought she preferred to study alone.C．He thought she had made arrangements to study withD．He had told her that he had done poorly on a recent test.

单项选择题A．People can call you back if necessary.B．You can dial a special number free.C．You don’’t need to pay for long distance call.D．You can get a credit coupon when you give the phone number.