Can "sed" substitute word on a specific line?

Shell Programming and Scripting
1

Hello experts,
I know line number of the word I want to replace. Can "sed" substitute word on a specific line?
As well, can sed substitute words inside a specific patten.
ex. <word>lalala</word> #replace anything between <word> and </word>

minifish

2

1)

sed -e "<line number>s/<search pattern>/<replacement string>/"

e.g. replace on line 4 the word "bike" by "car"

sed -e "4s/bike/car/"

2)
sed -e "s%\(<word>\).*\(</word>\)%\1<replacement string>\2%"
% is used instead of / so the / in front of the 2nd "word" doesnt need to be escaped.

or with /
sed -e "s/\(<word>\).*\(<\/word>\)/\1<replacement string>\2/"

3

thank you exper:D:b::b::b::b::b::b::b::b::b: