Although the causes of cancer_____, we do not yet have any practical way to prevent it.
| A．are being uncovered | B．have been uncovering |
| C．are uncovering | D．have uncovered |
We had a party _______ having class last Friday
| A．instead | B．but | C．instead of | D．still |
Don’t touch anything __________ your teacher tells you to.
| A．if | B．though | C．unless | D．even though |
Would you mind not ________ about me ?
| A．worry | B．worrying | C．worried | D．to worry |
All of us were ________ at the __________ news.
| A．frustrating, frustrating | B．frustrating, frustrated |
| C．frustrated, frustrating | D．frustrated, frustrated |
He is afraid of ___________ strangers.
| A．see | B．seeing | C．saw | D．seen |