Look before you leap! You have to ______the costs of the new system against the benefits it will bring.
| A．weigh | B．match | C．defend | D．Fight |
________is known to us all is that the 2012 Olympic Games will take place in London.
| A．It | B．What |
| C．As | D．Which |
________he couldn’t understand was________，as a teacher of Chinese，he was asked to teach history.
| A．What；that | B．What；what |
| C．What；which | D．Why；how |
________parents say and do has a lifelong effect on their children.
| A．That | B．Which |
| C．What | D．As |
________worries meis the way he keeps changing his mind.
| A．This | B．That |
| C．What | D．It |
________matters most in learning English is enough practice.
| A．What | B．Why |
| C．Where | D．Which |