________ (fail) several times, they need some encouragement.
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The floor does not look so bad when ________ (sweep) clean.
排球场区由前场区和后场区之分它们是以什么来区分的()
A. 场地的中间
B. 场地的中线
C. 限止线
We were busy ________ (get) things ready for the trial production when he phoned us.