双胎妊娠的并发症有（）

A.妊高征

B.前置胎盘

C.胎盘早剥

D.胎位异常

E.胎儿宫内发育迟缓

The（）schemeinadatabasesystemisresponsibleforthedetectionoffailuresandfortherestorationofthedatabasetoastatethatexistedbeforetheoccurrenceofthefailure.

A.query 

B.test 

C.check 

D.recovery