By the time he was ten,Edison______experiments in chemistry.
| A．had already done | B．already had done |
| C．was already doing | D．already did |
I can never forget the day ____we worked together and the day _____we spent together.
| A．when; which | B．which; when |
| C．what; that | D．on which; when |
—You ran into Mr. Li ! How did that happen?
—Well, _____ of us was looking where we were going. We came around the corner at the same time.
| A．neither | B．either | C．both | D．none |
Although ____ badminton is my favorite sport, I am not _____ very good player.
| A．the ; a | B．the ; the | C．/ ; a | D．/ ; the |
Does the way you thought of ________ the water clean make any sense?
| A．making | B．to make | C．how to make | D．having made |
As a result of destroying the forests, a large ________ of desert ________ covered the land.
| A．number; has | B．quantity; has | C．number; have | D．quantity; have |