121. I was uncertain of my success. Which of the following can replace the underlined word?
I recognized him __________ he appeared on the stage.
In the corner of the room __________.
I __________ agree with you yesterday but today I'm sorry.
The lawyer was looking through the documents __________ immigration laws.
A (n) __________ of scientists are looking into the matter and have realized a certain __________ of time is to be spent.