下面是一个简单的多路选择器，编译时候不通过，我应该怎么设置文件目录，还有编译的时候应该按照什么顺序以及应该注意什么，谢谢各位好心人

library ieee;
use ieee.std_logic_1164.all;
entity mux is
port(a1,a2,a3,s0,s1 :in std_logic;
outy ut std_logic);
end mux;

architecture behave of mux is
COMPONENT MUX21A
port(a，b，s:IN std_logic;
y:OUT std_logic);
END COMPONENT；SIGNAL tmp : STD_LOGIC;
begin
u1:mux21a PORT MAP(a=>a2，b=>a3，s=>s0，y=>tmp);
u2:mux21a PORT MAP(a=>a1，b=>tmp，s=>s1，y=>outy);
END ARCHITECTURE behave;

library ieee;
use ieee.std_logic_1164.all;
ENTITY mux21a IS
PORT(a,b,s:IN std_logic;
y:OUT std_logic);
END ENTITY mux21a;
ARCHITECTURE one OF mux21a IS
BEGIN
PROCESS(a,b,s)
BEGIN
IF s='0'THEN y<=a;ELSE y<=b;
END IF;
END PROCESS;
END ARCHITECTURE one;

先谢谢你，错误如下，我是建立了两个文件：mux21a在文件E：\mux21a文件下面，木mux在文件E：\mux下面，我先编译的mux21a能通过，再编译没木星mux的时候就报错了，我不知道元件例化的过程和编译顺序，请指教下，谢谢

Error (10500): VHDL syntax error at mux.vhd(10) near text ?
Error (10500): VHDL syntax error at mux.vhd(10) near text "?; expecting ":", or ","
Error (10500): VHDL syntax error at mux.vhd(10) near text ?
Error (10500): VHDL syntax error at mux.vhd(12) near text ?
Error (10500): VHDL syntax error at mux.vhd(12) near text "?; expecting ";", or an identifier
Error (10500): VHDL syntax error at mux.vhd(12) near text ?
Error (10500): VHDL syntax error at mux.vhd(16) near text ?
Error (10500): VHDL syntax error at mux.vhd(16) near text "?; expecting ")", or ","
Error (10500): VHDL syntax error at mux.vhd(16) near text ?
Error (10500): VHDL syntax error at mux.vhd(17) near text ?
Error (10500): VHDL syntax error at mux.vhd(17) near text "?; expecting ")", or ","
Error (10500): VHDL syntax error at mux.vhd(17) near text

谢谢楼上的，由于是初学，还有很多问题不明白，真的很感谢

学习了 谢谢