He trained hard in puzzle-guessing, a sort of children’s game, all year, _____ still failed to reach his best form in all the tests given to both adults and children.

A．Then 　　　　　

B．Thus 　　　　

C．Therefore

D．Yet

以下不属于国际争端解决的政治方法的是：

A．谈判与协商

B．斡旋

C．调查

D．仲裁