31.The company had about 20 notebook computers but only one third _______used regularly . Now we have 60 working all day long.
| A．is | B．are | C．was | D．were |
With the second ring road overpass _______ at present in Chengdu, the local citizens have to choose another way to avoid traffic jam.
| A．being constructed | B．to construct | C．to be constructed | D．to be constructed |
I missed the last bus and had no money for a taxi; so I could do nothing but_______ home last night.
| A．to walking | B．walk | C．walking | D．walked |
Who do you think will _______ since the president has resigned?
| A．take over | B．take up | C．take in | D．take off |
--How was your weekend, Rose?
--Awful! This was the first time I ________ alone at home, bored to death.
| A．had left | B．had been left | C．have been left | D．have been leaving |
Many citizens urged their government to take measures to _______ their carbon emission to reduce greenhouse effects.
| A．cut off | B．cut up | C．cut out | D．cut down |