—When did your cousin begin to show his interest in medicine?—It was a Saturday __________ she noticed her uncle experimenting on a frog in his lab.
---Who will address the students from our school this evening? --- ______ to be the speaker.
Tommy had had a three-mile drive north _____ he could turn and head back south.
The scientists all agreed that rules of physics, ______ we are all familiar, govern the world.
To keep safe _______ an earthquake, you should remain at a spot in your room where nothing may fall on you.
—I will come to attend your lecture at 10:00 tomorrow.—I’m sorry, by then my lecture will have ended and I _____ in my office.