I feel the house shaking.—-So do I .It ___ be sign of an earthquake most probably. Let’s hurry to leave here.

You look tired, you should have a good rest for _______ days.— That sounds good.

She has beento Shanghai, has she

Scientists are racing________time in order to find a cure for bird flu.[ ]

One-third of the area _____ covered with trees. About seventy percent of the trees _____ been planted recently.