Fill in the blank with one appropriate preposition to complete the following sentence :

You have to put ... your toys and go to bed. It's too late.

Fill in the blank with one appropriate preposition to complete the following sentence :

I'm very grateful ... you ... your invaluable help.

Fill in the blank with one appropriate preposition to complete the following sentence :

What a pity! We left him ... saying goodbye.

Fill in the blank with one appropriate preposition to complete the following sentence :

Clean air provides us ... a healthy supply of oxygen.

Ultimately, you'll have to make the decision yourself.

A. Consequently  B. Basically  C. Generally  D. Finally