The author doesn’t seem to believe ________.
A. children will be on time if they have learnt how to tell time
B. a Flik Flak can help parents teach their children how to tell time
C. the Flik Flak can capture children’s imagination
D. children usually have trouble telling time if they don’t wear watches
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下列关于计算VAR的方差一协方差法的说法,不正确的是()