The $IUPAC$ name of the compound $CH_3-C(CH_3)_2-CH_2-CH=CH_2$ is:

Fill in the blanks:
$(1)$ The $IUPAC$ names of $CH_3COOCH_3$ and $CH_3CH_2COOCH_3$ are ....... and ....... respectively.
$(2)$ ....... isomers of dibromobenzene exist.
$(3)$ ........ is the $IUPAC$ name and ........... is the common name of $C_6H_5OCH_3$ respectively.
$(4)$ The structure of $1-$chloro$-2,4-$dinitrobenzene is shown below.

The $IUPAC$ name of $CH_3CH_2COCl$ is

Which of the following is correct according to the $IUPAC$ nomenclature?

Fill in the blanks:
$(1)$ The $IUPAC$ name of $CH_3COCH_2CH_2CH_2COOH$ is .........
$(2)$ The formula of pent$-4-$en$-2-$ol is .........
$(3)$ The $IUPAC$ name of the following structure is ......... and ......... is the main functional group in it.
(Structure: $A$ cyclohexene ring with an $-OH$ group attached to the carbon adjacent to the double bond,such that the double bond is between carbons $2$ and $3$ relative to the $-OH$ at position $1$.)
$(4)$ For $CH_3CH(OH)CH_2CH_2CH_2CHO$,the main functional group and the second priority group are ......... and ......... respectively.

What is the $IUPAC$ name of the compound $CH_3-CH(OH)-CH_2-CH(CH_3)-CH_3$?