问题

nping’s report, ” a smile on his face, hecontinued, “_____ to several hot topics, discusses how to increase farmers’income”
A:slipped; was noticing
B:had slipped; noticed
C:slipped; had noticed
D:was slipping; noticed
B:had slipped; noticed
C:slipped; had noticed
D:was slipping; noticed
正确答案是: