Categories are regular classes containing static methods.

categories是一个常规类，包含静态方法。

youdao

Ding has yet to pass the final stage and hopes to begin regular classes in the spring.

丁先生尚未通过最后阶段，希望在春季开始一般课程。

youdao

Mr. Ding has yet to pass the final stage and hopes to begin regular classes in the spring.

丁先生尚未通过最后阶段，希望在春季开始一般课程。

youdao

But the regular classes, their level is lower than in Turkey."

VOA: special.2009.11.05

Many,however,are able to attend regular classes with other students.

VOA: special.2009.09.09

If regular classes with supplementary aids and services do not help a child with special needs, the child does have a right to attend special classes or separate schooling free of charge.

FORBES: Parent-Teacher Meetings Critical for a Child with Special Needs Education

About 10 percent of the students attend regular classes at those schools, with an aide to help them, but 90 percent are in special classes, with student-teacher ratios as small as 1-to-1 and as large as eight students with two aides and one teacher.

CNN: From P.S. 176X, kids with autism get joyful launch

It was a blind man, Bob Gildea, who got me "hooked" on braille in 1969, enlisting me as a computer programmer on a joint MIT-Mitre Corporation project that allowed teachers within the Atlanta schools to have materials quickly translated into braille for blind students integrated into regular classes.

WHITEHOUSE: Providing Literacy for Informed Citizenry through Braille | The White House