北约在对南联盟进行轰炸时，大量使用贫铀炸弹．贫铀比重约为钢的2.5倍，设贫铀炸弹
题型：选择题
问题：
北约在对南联盟进行轰炸时，大量使用贫铀炸弹．贫铀比重约为钢的2.5倍，设贫铀炸弹与常规炸弹射行速度之比约为2：1，它们在穿甲过程中所受阻力相同，则形状相同的贫铀炸弹与常规炸弹的最大穿甲深度之比约为（ ）
A．2：1
B．1：1
C．10：1
D．5：2
题型：选择题
The Grade 3 students at the Clean City School collect empty bottles .In June ,they are going to take them to a recycling () center .They are going to sell the bottles and buy some books for the school library.
Kate has started a graph (图表) to show the number of the bottles they have collected . This is the graph .
Student Bottle Collection
The months of the School Year
小题1:In October the students collected ______ empty bottles.
A．80
B．60
C．40
D．20小题2:The students collected _____ more bottles in December than in January .
A．10
B．20
C．30
D．40小题3:Form the graph above ,we know that the students picked up the same number of bottles in ______ and ______ .
A． October ;February
B．September ;April
C．January ;May
D．November ; March小题4:Why do the students collect empty bottles ? Because they ______ .
A．want to do something for their school
B．like empty bottles very much
C．want to play with the bottles
D．want to sell them to buy balls小题5:How many bottles have they collected in November?
A． 20
B．40
C．60
D．80