要用java写这个程序..
if x is null then prompt the user and read x
if x is not null and is bigger than 39 then print〝too big〞and make x by 10
if x is not null and is between 10 and 39 then print〝X〝and reduce x by 10
if x is not null and is equal to 9 then print〝IX〞and reduce x to 0
if x is not null and is between 5 and 8 then print 〝V〝and reduce x by 5
if x is not null and is equal to 4 then print 〝IV〝and reduce x to 0
if x is not null and is between 1 and 3 then print 〝I〝and reduce x by 1
if x is not null and is equal to 0 then print an end-of-line and make x null.
用自由的顺序判断条件真假..直到条件为ture为止..
ture的时候执行什么命令
重复操作

看英文部分蛮简单，到了中文部分我看不懂了．