A.25個(gè) B.15個(gè) C.20個(gè) D.5個(gè)
A.h=4.2m,1次不斷或h=3.1m,2次不斷 B.h=4.2m,1次不斷或h=2.5m,2次不斷 C.h=6.4m,1次不斷或h=2.5m,2次不斷 D.h=5.2m,1次不斷或h=3.1m,2次不斷
A.2m~4m B.1m~3m C.1m~2m D.2m~3m