问答题

百分表测头工作面的表面粗糙度中对钢质的测头应不大于Ra（）m，对硬质合金的测头应不大于Ra（）m

答案：百分表测头工作面的表面粗糙度中对钢质的测头应不大于Ra 0.4μm，对硬质合金的测头应不大于Ra 0.2μm。百分表是一...

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单项选择题

/p/ and /b/ can appear in initial position (as in pin and bin) and also in final position (as in rope and robe)．They are in phonemic contrast and said to form a _______________ because they occur in the same environment and distinguish meaning.
A、complementary distribution
B、allophonic distribution
C、minimal pair
D、segmental phoneme

以下关于盐沼的说法，哪个是正确的？

答案： A、没有动物生存B、含有大量盐分正确答案：B答案解析：盐沼是指含有大量盐分的湿地。它形成于受海水影响大、地势低洼且排水不...