Jenny nearly missed the flight _____ doing too much shopping. [ ]

A. as a result of

B. on top of

C. in front of

D. in need of

采用微生物法测定的食物中的维生素PP，主要包括

A.烟酸

B.叶酸

C.烟酰胺

D.吡哆醇

E.吡哆醛