It will help you better understand tenses , prepositions , and all the other parts of speech we normally take for granted .
知晓另一种语言让我们可以比较，有助于更好地理解时态，介词，还有那些我们通常想当然的语法成分。
His prosthesis works by using two electrodes that make contact with the skin on his upper arm . When he tenses a muscle , tiny pulses of electricity from the nerves beneath the electrodes cause the hand to close ; when he tenses another , the hand opens .
