all of them are strong candidates only one will be chosen for the post.A. SinceB. WhileC.

问题补充：

all of them are strong candidates, only one will be chosen for the post.

A. Since

B. While

C. If

D. As

答案：

A. Since

(答案→)B. While

C. If

D. As

解析： 考查连词。Since由于，既然；While尽管；If如果；As尽管。句子前后是转折关系所以排除A,C;as当尽管讲时，引导让步状从要用倒装结构，而all of them are strong candidates,是正常语序，所以选B。