下列运算正确的是( )
A:b5+b5=b10
B:(a5)2=a7
C:(-2a2)2=-4a4
D:6x2·(-3xy)=-18x3y
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______ earthquake happened on ______ morning of April 14th in Yushu, Qinghai. By far, over 2,000 people have died.