He wondered if he could slip out of the lecture hall without anyone______.
The traditional approach ____ with complex problems is to break them down into smaller, more easily managed problems.
Someone called me up in the middle of the night, but he hung up ____ I could answer the phone.
------ What made little Tony so unhappy and cry in his room? ------- _________to go biking with his brother.
----- Sally is strongly against taking the trip to Hainan. ----- _______? It was she who suggested the plan.
Was it not until you began to work ____ how much time you had wasted?