A.山頂點(diǎn)B.凹陷點(diǎn)C.平地點(diǎn)D.地底點(diǎn)
A.1個(gè)B.2個(gè)C.3個(gè)D.無數(shù)個(gè)
A.小于150mmB.150mmC.大于300mm