What is the main topic of the passage?
A.A revolution in communication
B.The invention of optical fibers
C.New surgical techniques
D.The roles of optical fibers in medicine

His policies were beneficial to the economy as a whole.
A.harmless
B.crude
C.detrimental
D.innocent

A.certificate
B.available
C.appropriate
D.absolutely

A.monitor
B.depiction
C.desperate
D.fabulous

I am tired from staying up late last night studying. I am also worried about today’s test.
A.I am not only tired of staying up late last night studying but also worried about today’s test.
B.Tired from staying up late last night studying, today’s test also makes me worried.
C.Not only am I tired from staying up late last night studying but I am also worried about today’s test .
D.Because I am worried about today’s test, I stayed up late last night studying.

My grandparents’ lake house was built in 1953. It was completely destroyed by the forest fire.
A.My grandparents’ lake house was built in 1953 and completely destroyed by the forest fire
B.My grandparents’ lake house, built in 1953, was completely destroyed by the forest fire
C.My grandparents’ lake house was built in 1953, so it was completely destroyed by the forest fire
D.The forest fire destroyed my grandparents’ lake house was built in 1953.

Travellers are advised to take out insurance. Their luggage may go astray.
A.Travellers should take out insurance if their luggage goes astray.
B.Travellers should get insurance, or else their luggage may go astray.
C.Travellers had better buy insurance as a precaution against their luggage go astray.
D.Travellers are advised to take out insurance in case their luggage goes astray .

As we were heading out of the café, we bumped into our plumber, who we still owed money to.
A.Our plumber, whom we hadn’t paid back yet, was the person who we encountered by chance at the moment we were exiting the café .
B.When we met our plumber in the café as we were about to leave, we realised that we hadn’t yet paid him all the money we owed him.
C.Our plumber, when we ran into him as he was entering the café that we were leaving, didn’t bring up our debt to him.
D.Not wanting to see the plumber to whom we still owed a debt, we quickly headed out of the café when we saw him coming in.

The burglar was caught red-handed by the police when he broke into the flat.
A.The police caught the burglar breaking into the flat .
B.The police caught the burglar to break into the flat.
C.The police caught the burglar when breaking into the flat.
D.When the burglar had broken into the flat, the police caught him at once.

The fox tried, but was unsuccessful in reaching the grapes.
A.The fox tried in vain to reaching the grapes.
B.Hard as he tried, the fox couldn’t reach the grapes .
C.Try as he may, the fox failed to reach the grapes.
D.Despite of the effort he made, the fox found the grapes impossible to reach.