现有3cm,4cm,7cm,9cm长的四根木棒,任取其中三根组成一个三角形,那么可以组成的三角形的个数是 [ ]
A.1个
B.2个
C.3个
D.4个
答案:B
82与15的差乘18,积是多少?
A society was set up to________the endangered animal and plant life from dying out in this area. [ ]
A. reserve
B. preserve
C. observe
D. deserve