再问OG72

72. The number of undergraduate degrees in engineering awarded by colleges and universities in the United States( increased by more than twice )from 1978 to 1985.
A. increased by more than twice
B. increased more than two times
C. more than doubled
D. was more than doubled
E. had more than doubled

请问答案C:他的谓语是什么？感觉没有系动词啊，难道谓语是doubled?那more than是什么成份啊。。。

72. The number of undergraduate degrees in engineering awarded by colleges and universities in the United States increased by more than twice from 1978 to 1985.
C. more than doubled

改后谓语确实是doubled, double是动词。