when I run my script,the engine tell me that the script missing a bracket in the last line,but I don't miss it.And it aslo say unknown all the strings that I defined,why?

Without some code it's impossible to say what could be wrong. For now I suppose the compiler is correct.

the first .wdl include the second .wdl,the engine say the second .wdl missing a bracket on the last line,and the unknown the strings defined in the first .wdl.
If I use the third .wdl include the second one,then the engine say the second one missing the bracket,but say unknown the strings defined in the third one.

main.wdl Code:

---

include "second.wdl";

TEXT myText
{
	layer = 1;
	pos_x = 10;
	pos_y = 10;
	string = firstString;
	flags = VISIBLE;
}

function main()
{
	level_load("");
	wait(1);
}

---

second.wdl Code:

---

STRING firstString = "Some string";

---

No problem. Anyways, unless you show your code it's not possible to help.