Jakey

Hi，感谢你写的api，我在使用中遇到需要并发执行翻译任务。代码逻辑中控制了并发10个，但是最近会频繁遇到报错如下： ``` panic(0x1386d40, 0xc0001cc0e0) /usr/local/Cellar/go/1.14.5/libexec/src/runtime/panic.go:969 +0x166 github.com/jinzhongmin/gtra.gettkk(0xc0005540c6, 0xc000125d50) /Users/jakehu/go/pkg/mod/github.com/jinzhongmin/[email protected]/gtra.go:113 +0x1bb github.com/jinzhongmin/gtra.tk(0x13b0714, 0x6, 0x53, 0x13af6f3) /Users/jakehu/go/pkg/mod/github.com/jinzhongmin/[email protected]/gtra.go:101 +0x26 github.com/jinzhongmin/gtra.getResult(0x13b0714, 0x6, 0x13afb75, 0x4, 0x13af4b2, 0x2, 0xc000125e20, 0x1, 0x1, 0xc000125e68, ...) /Users/jakehu/go/pkg/mod/github.com/jinzhongmin/[email protected]/gtra.go:177 +0x25b github.com/jinzhongmin/gtra.(*Translater).Translate(0xc000125eb0,...