关于妊娠合并重度缺铁性贫血对胎儿的影响，不正确的是 （）

A.当孕妇患有重度贫血时可导致胎儿窘迫

B.当孕妇患有重度贫血可引起胎盘缺血而发生胎儿发育畸形

C.当孕妇患有重度贫血时可导致早产

D.当孕妇患有重度贫血时可导致死胎

E.当孕妇患有重度贫血时可导致胎儿生长受限

A high-velocity fog stream can be used in fire fighting situations to drive heat and smoke ahead of the fire fighters in a passageway. This technique should only be used when（）.

A.using a 2-1/2 inch hose

B.there is an outlet for the smoke and heat

C.the fire is totally contained by the ship's structure

D.at least two fog streams can be used