When asked to explain ________ made his lessons so exciting, the teacher kept silent.
| A．what it was that | B．that what it was |
| C．what was it that | D．that what was it |
Perhaps it is true that nobody in the world knows exactly how the earth _____.
A. came up B
. came out C. came to power D. came into being
She is very _______ about this topic, so we’d better not discuss it in front of her.
| A．confident | B．crazy | C．sensitive | D．humorous |
I suggested that they set off early to avoid (避开) the traffic jam, _______ no one responded.
| A．on which | B．to which | C．about which | D．for which |
Nowadays, use____________of certain waste materials to protect the environment.
| A．is making | B．will make | C．is being made | D．will be made |
He has been heavily _______ to the bank since he bought that big house in Beijing.
| A．in debt | B．in peace | C．in danger | D．in cash |