您有灌好carryforward吗？
我测试没问题说。

inp x
1
.
.
2
.
.
3
end

carryforward x,replace
l

我按照您的命令，提示：unrecognized command:  carryforward
r(199);
这是怎么一回事呀？

You need to install carryforward first.

Try the following command in your Stata command line.

ssc install carryforward

If you don't want to install carryforward, you may want to look at this page for more help.

http://www.stata.com/support/faq ... ing-missing-values/

Thanks a lot!

carryforward 这个外部命令还是下载不下了。

. ssc install carryforward
connection timed out -- see help r(2) for troubleshooting
http://fmwww.bc.edu/repec/bocode/c/ either
  1)  is not a valid URL, or
  2)  could not be contacted, or
  3)  is not a Stata download site (has no stata.toc file).
r(2);