形式变换：形容词形式是theoretical，例如：

1、The first year provides students with a sound theoretical basis for later study.第一年为学生以后的学习奠定坚实的理论基础。

2、The course is essentially theoretical in orientation.该课程的目标基本上是理论性的。

3、It's a theoretical possibility.这是理论上存在的可能性。