On Sundays there were a lot of children playing in the park, __ parents seated together joking.
A:whose
B:their
C:which
D:that
下列会引起细菌性食物中毒的是( )
①陈独秀 ②李大钊 ③鲁迅 ④胡适 ⑤***
设e→是单位向量,AB→=3e→,CD→=﹣3e→,|AD→|=3,则四边形ABCD( )