It means this tennis ball... while it is in free fall, it has no weight.
再比如说这个网球。，自由落体过程中它没有重量。
If you want to keep the weight down, switch to a meat-free diet, scientists said.
科学家说，希望体重持续减轻，就改吃无肉饮食。
If you want to keep the weight down, switch to a meat-free diet, scientists said.
科学家说，希望体重持续减轻，就改吃无肉饮食。
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