_________ did the students realize that they were mistaken about spiders.
| A．It was until then | B．It was not until then |
| C．Not until then | D．Not until when |
In Singapore, people______eating or drinking on the subway can be fined up to 500 Singapore dollars.
| A．having caught | B．catching |
| C．caught | D．to catch |
The zookeeper was really annoyed with me.
— How could he have been if you______stones at the animals?
| A．didn’t throw | B．don’t throw |
| C．hadn’t thrown | D．haven’t thrown |
—What do you do as a volunteer in North Africa?
—__________! There are many poor people who need a lot of help.
| A．None | B．Something |
| C．Little | D．Everything |
They’ve moved to a different house_________their children can attend a better school.
| A．in case | B．so long as |
| C．so that | D．even though |
The Alibaba Group, _____was founded in 1999, has become China’s largest e-commerce company.
| A．what | B．which | C．whose | D．whether |