Polar explorers have to be extremely _____ to bear the climate and other hardships.
| A．tough | B．rough | C．difficult | D．brave |
She won’t be able to come next week, because she_________herself in Mount Tai then.
| A．enjoys | B．will be enjoying | C．is enjoying | D．enjoyed |
When a student asks__________it is worth staying up doing their lessons, a teacher may find it difficult to answer.
| A．that | B．what | C．whether | D．how |
Mr. Li arrived at the Wuguang train station twenty minutes ago, but the train to Guangzhou_______yet.
| A．hadn’t come | B．won’t come | C．hasn’t come | D．didn’t come |
To pass the driving test, Alice had a busy month driving the car.
| A．to practise | B．practising | C．practised | D．practise |
How can they expect to learn anything_________they never listen?
| A．when | B．until | C．unless | D．though |