矿井内的气体状况每半小时就取样一次，救援人员说，他们需要一个持续下降的趋势，专业救援小组才能进入矿井。
Samples of gas conditions in the mine are being taken every half hour and rescuers say they need a sustained downward trend before specialist rescue teams could enter.
每半小时我就停下来去吸支烟。?。
为了防止温度过高，转动房子的发动机每工作20分钟就自动停机半小时。旋转间歇，房客可以在屋顶露台上歇息(见图)。
The motor stops automatically for half an hour after 20 minutes of rotating the room, to avoid overheating. Between spins, guests can relax on the rooftop patio (see photo).
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