We understand _______small changes to our land can have a big impact upon our environment __________ as we know is vulnerable enough.
| A．what; which | B．what; where | C．how; where | D．how; which |
He had been so absorbed __________ watching the carpassing by that he didn't notice his friends __________.
| A．to；coming | B．in；to come | C．on； coming | D．in； coming |
According to a UN report, some 844 animals and plants __________ in the last 500 years.
| A．disappeared |
| B．were disappeared |
| C．have disappeared |
| D．had been disappeared |
—Have you finished the book? —No. I've read up to __________ the children discover the secret cave.
| A．which | B．what | C．that | D．where |
When I opened the door, I found my father sitting in his chair, completely __________ in the humorous stories he was reading.
| A．absorbed | B．losing | C．attracted | D．addicted |
Before __________him, Icalled him __________.
| A．visiting；in advance |
| B．visit；in advance |
| C．visiting ； advance |
| D．visit； advance |