早孕最常并发的盆腔肿块是（）。

A.子宫肌瘤

B.黄体囊肿

C.皮样囊肿

D.内膜囊肿

E.滤泡囊肿

All passengers ____, please fasten your seat belts and remain seated ____the plane is landing．

A．on board; until

B．abroad; since

C．on the board; before

D．aboard; when