Don’t lose heart you fail.A. until　B. as if　C. unless　　D. even though

问题补充：

Don’t lose heart you fail.

A. until

B. as if

C. unless

D. even though

答案：

A. until

B. as if

C. unless

(答案→)D. even though

解析：句意,即使失败了也不要丧失信心。until直到……为止;as if好像;unless 除非; even though即使.故选D.