—_____ does your father go to the fitness center?
—He exercises there twice a week.
| A．How soon | B．How often |
| C．How long | D．How far |
_______ was a struggle for me to remember all the strange faces and new names.
| A．It | B．That | C．There | D．This |
Mountain climbing _______ be tiring and many people feel sick as the atmosphere gets thinner.
| A．need | B．can | C．must | D．would |
Now she is considering taking some weight-loss pills, _______ she thinks will help her become slim.
| A．which | B．that | C．what | D．who |
The _______ boy made the police and his family _______.
| A．gone; puzzled | B．missing; puzzled |
| C．missing; puzzling | D．lost; puzzling |
_______ his studies, he started travelling in China.
| A．As soon as finish | B．As soon as finishing |
| C．Upon finishing | D．Upon finish |