Not until I began to work ________ how much time I had wasted.
Some researchers believe that there is no doubt ______ a cure for AIDS will be found.
The place _______ the bridge is supposed to be built should be________the cross-river traffic is the heaviest.
The shopkeeper did not want to sell for ________ he thought was not enough.
Danby left word with my secretary ________ he would call again in the afternoon.
Do you have any ideas ________ is actually going on in the classroom?