This is a paraphrasing task. In this task, you're given a sentence and your task is to generate another sentence which express same meaning as the input using different words.
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Question: the main issues are high cost , low energy density and heavy weight of batteries .

Answer: the main problems are high costs , low energy concentrations and a high battery charge , which greatly limits the commuter distance .

Question: she sat on the rock like it was a chair and used her good leg and the crutch to push herself upward , a foot at a time .

Answer: she sat down on the rock , as if it were a chair and using a healthy leg and the cane moved up , down the track .

Question: i do n't doubt your abilities , b'elanna ... but helping them reproduce is a clear violation of the prime directive .

Answer:
i acknowledge your skills , b'elanna ... but thus helping them to reproduce is a clear violation of the directive .