16. _______ medicine works in a human body is a question _______ not everyone can understand fully.
| A．How; that | B．That; which |
| C．That; which | D．What; that |
The mayor will go to Beijing by train _____ by air.
| A．instead of | B．instead | C．in place of | D．in place |
Living in a big city has many _____, such as good schools, libraries and convenient traffic.
| A．goodness | B．advantages | C．effects | D．uses |
Father _____ goes to the gym with us although he dislikes going there.
| A．hardly | B．seldom | C．sometimes | D．never |
– I’m very tired.
– We really should stop _____.
| A．to walk | B．walk | C．walking | D．walked |
WHO is short _____ the World Health Organization.
| A．of | B．for | C．to | D．with |