Down. Do not use down as a verb in the sense of defeat or overthrow.

Wrong: Our football team has downed every other team in the state.
Right: Our football team has defeated every other team in the state.

Drownded. Drownded is not a proper form of the verb drown. Say drowned. (Pronounced drownd.)

Each other. Do not use each other to refer to more than two objects. See §44.

Wrong: The members of the regiment helped each other.
Right: The members of the regiment helped one another.

Effect, affect. Do not confuse effect and affect. Effect means a result, or to cause a thing to be done. Affect means to disturb or have an influence on.

Wrong: The news effected him seriously.
Right: The news affected him seriously.
Wrong: The affect of this news was to cause war.
Right: The effect of this news was to cause war.

Either. Do not use either with reference to more than two objects, nor follow it by a plural verb. See §43.

Wrong: Either of the three will do. Either you or John have done it.
Right: Any one of the three will do. Either you or John has done it.