本课配套习题挑战模式1/5

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单选题
难度系数:

1.用大小相同的小三角形摆成如图所示的图案,按照这样的规律摆放,则第n个图案中共有小三角形的个数是(    ).
A: 3n+4
B: 2n+4
C: 3n-4
D: 3n+2
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