For a linear regression model with i.i.d. sample: , under conditional heteroskedasticity, usually which of the following statement does not hold: A、OLS estimator is the best linear unbiased estimator B、consistency C、asymptotic normal D、a robust test should be used, rather than the standard test
, under conditional heteroskedasticity, usually which of the following statement does not hold:
test should be used, rather than the standard 
test
