赞题库-背景图

单项选择题

丫一△减压起动的指电动机起动时，定子绕组丫联结，以降低起动电压，限制起动电流。待电动机起动后，再把定子绕组改成（），使电动机全压运行。
A、YY联结
B、Y△联结
C、△△联结
D、△联结

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单项选择题English and German have relatively large vowel inventories. What reason does the discussion provide for this

A．These languages tend to have a simpler syllable structure than other languages, and need more differences between vowels.
B．Earlier distinctions between long and short vowels developed into vowel quality contrasts in these languages.
C．Because of extensive language contact, these languages borrowed vowels from each other.
D．These languages have a long writing tradition, influencing the number of vowels that can be expressed.
E．These languages are relatively old and had more time to develop the vowel inventory.