I didn’t quite follow him because he explained the theory _____that is too abstract for me.
— Thanks a lot for your book. I found it very interesting.— ______. I’m glad you enjoyed it.
You can hardly imagine how excited I was when the day I had been looking forward to _____ at last.
The effect a teacher has _______ children may be greater than that of their parents.
—Everyone in my class passed the exam.—Oh, really? It ________ difficult.
I ran across David while walking along the street yesterday. I ________ him for three years.