Wateriscomposed_______hydrogenandoxygen.
A、ofA
be composed of：由 …组成。句意：水是由氢与氧化合而成的。
Thetwogirlscompetedwitheachother______thehighestmark.
Theypreferto_______therestofthemorningwalkinginthegarden.
Aftermonthsofvoyage,Columbusarrivedin______laterprovedtobeanewcontinent.
Theboycomplained_______apaininhisstomach.
Hewas______towithdrawfromrunningforthepresidency.
