计算:(x3-2x2y)÷(-x2)
(x3-2x2y)÷(-x2),
=x3÷(-x2)-(2x2y)÷(-x2),
=-x+2y.
下列各式中,正确的是[ ]
A.x2y﹣2x2y=﹣x2y
B.2a+3b=5ab
C.7ab﹣3ab=4
D.a3+a2=a5
细料、剧毒药发放,需精确称量至()
A.1g
B.0.01g
C.0.5g
D.0.1g