Whispering Inc. uses a calendar year for financial reporting. The company is authorized to issue $8,420,000$ shares of $$12$ par common stock. At no time has Whispering issued any potentially dilutive securities$.$ Listed below is a summary of Whispering's common stock activities.

Number of common shares issued and outstanding at December $31,2018$

$2,010,000$

Shares issued as a result of a $12\%$ stock dividend on September $30,2019$

$241,200$

Shares issued for cash on March $31,2020$

$2,060,{000}_{?}$

Number of common shares issued and outstanding at December $31,2020$

$4,311,{200}_{{?}_{?}}$

A $2-$for$-1$ stock split of Whispering's common stock took place on March $31,2021$

$($A$)$ Compute the weighted$-$average number of common shares used in computing earnings per common share for $2019$ in the $2020$ comparative income statement

$($B$)$ Compute the weighted$-$average number of common shares used in computing earnings per common share for $2017$ on the $2017$ comparative income statement

$($C$)$ Compute weighted$-$average number of common shares to be used in computing earnings per common share for $2017$ on the $2018$ comparative income statement

$($D$)$ compute the weighted$-$average number of common shares to be used in computing earnings per common share for $2018$ on the $2018$ comparative income statement