Hewas______towithdrawfromrunningforthepresidency.
Copernicusmaintainedthattheearth_____roundthesun.
Aftermonthsofvoyage,Columbusarrivedin______laterprovedtobeanewcontinent.
羊膜镜检查时观察到羊水的正常颜色是（）
Mrs.Smithlockedboththefrontandthebackdoorsbeforeshewenttobed______thatsomeonemightstealintothehouseatnight.
