计算:2x3•x2等于( )
A:2
B:x5
C:2x5
D:2x6
读澳大利亚和美国本土农业带分布图及两国地形剖面图,完成以下题目:
Some damage has been caused u____ by people simply walking around the site and some has been caused deliberately.
计算:2xy2﹣3xy2=____ .