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

A．The US should catch up to European environmental standards.
B．American exporters must adapt to new regulations in Europe.
C．The US should be more sensitive to environmental issues.
D．The EU’s new regulations are a burden.