He is a teacher. He has been a teacher _____ 1990 and he _____ by his students.[ ]

A. in, is loved

B. until, loves

C. since, is loved

D. for, has loved

如将喷油泵壳体顺着凸轮轴旋转方向转动一角度,则供油迟后,供油提前角减小。