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 |
He was honest and told us ______ he knew.
| A．that that | B．what what |
| C．all all | D．which which |
She may have missed the train, in _______ case she won’t arrive for another hour.
| A．whose | B．that | C．which | D．what |
The best job is _____ which uses your skill in doing something together with your interest in the subject.
| A．something | B．the one | C．one | D．it |
Living in the central Australian desert has its problems, _____ getting water is not the least.
| A．for which | B．to which |
| C．of which | D．in which |
_____ could be judged from what he had said, he felt terribly sorry for what he had done.
| A．Which | B．That | C．As | D．It |