Teachers have to constantly update their knowledge in order to maintain their professional ________．

A．consequence

B．independence

C．competence

D．intelligence

Saving and recycling are long-term projects ________ determination matters a great deal．

A．that

B．which

C．whose

D．where

Jack wasn't saying anything，but the teacher smiled at him ________ he had done something very clever．

A．as if

B．in case

C．while

D．though

US President Barack Obama ________ a national speech at the 10th anniversary of 9/11 terror attacks．

A．addressed

B．delivered

C．spoke

D．recited

Mistakes don't just happen; they occur for a reason．Find out the reason, and then making the mistake becomes ________．

A．favorable

B．precious

C．essential

D．worthwhile

________ Olympic torch has reportedly stayed alight throughout ________ varied extreme weather conditions in a German testing center．

A．不填; the

B．The; 不填

C．不填; an

D．The; a

________ to nuclear radiation, even for a short time, may produce variants of genes in human body．

A．Exposed

B．Being exposed

C．Having exposed

D．After being exposed

At a rough estimate, Nigeria is ________ great Britain．

A．twice big as

B．as twice big as

C．three times the size as

D．three times the size of

________ to give up smoking, he threw away his ________ cigarettes．

A．Determined; remained

B．Determining; remaining

C．Determined; remaining

D．Determining; remained

The order came ________ the soldiers ________ the small village the next morning．

A．that; had to leave

B．that; should leave

C．\; must leave

D．when; should leave