You___have come to the concert. It was excellent.A. mayB. needC. ought toD. must

in the last twenty years.

A. takes

B. took

C. have taken

D. should taken

It will not be long before everyone___the importance of computer skills at work.

A. will see

B. have seen

C. sees

D. would see

The problem of global warming___for decades.

A. has been existed

B. has existing

C. being existed

D. has existed

Lowering personal production of waste___everyone over the past decade.

A. benefited

B. has benefited

C. benefits

D. benefiting

Let everybody___something to reduce environmental pollution.

A. do

B. to do

C. doing

D. do it

ng carbon footprints.

A. will often see

B. often see

C. are often seeing

D. have often seen

___good care, the electrical devices in the area all work well.

A. Regarding

B. Thanks to

C. Like

D. Thanks for

If the lights were on, they___have been at home.

A. must

B. need

C. shall

D. would

The guest presented ______ that a staff in the hotel had stolen her pack.

A.proof

B.proofs

C.prooves

D.proofes

The manager demands that I meet five ___ at the exhibition tomorrow.

A.Australians

B.Australia

C.Australias

D.Australian