—______. They tasted delicious.
A:Yes, they did
B:No, they didn't
C:Yes, they were
D:No, they weren't
名著阅读。
一项工程,甲队独做需要20天完成,乙队独做需要30天完成.现在由甲队施工一天,然后由乙队接替甲队施工一天,第三天再由甲队接替乙队施工一天…,如此交替,最后乙队结束工作,多少天完成任务?