—Tom, your foreign teacher speaks Chinese fluently!—Oh, she has lived in China for six years, otherwise she _______ such good Chinese.
When I called you this morning, nobody answered the phone. Where ________?
—Did Alan enjoy seeing his old friends yesterday? —Yes, he did. He ________ his old friends for a long time.
—Will you go to the park now? —Not until I ________ my physics exercises.
Unfortunately, when I dropped in, Professor Smith ________, so we only had time for a few words.
—Does Liu Hui serve in the army? —No, but he ________ in the army for three years.