【1】What was surprising to us was(that省略) the biggest predictor was not whether they had exerted self-control .

备注(1)：以上句子中的“surprising”为(分词)形容词用法，使用结构“sth be surprising to sb”意思为“某事对某人来说是出人意料的”

备注(2):What was surprising to us 为融合性关系代词what引导的名词性关系分句作主句的主语，即主语从句。（what=the thing that）what在主语从句作主语。

备注(3):(that省略) the biggest predictor was not whether they had exerted self-control .为从属连词that引导的表语从句。The biggest predictor为表语从句主语，wasn’t为系动词否定结构，whether they had exerted self-control .为that表语从句的表语，这个表语也是由连词whether引导表语从句。

【2】What was surprising us was(that省略) the biggest predictor was not whether they had exerted self-control .

备注(1)：以上句子中的“surprising”为及物动词(surprise)现在分词用法，使用结构“sth surprise sb”意思为“某事使某人感到意外/某事使某人吃惊/惊奇”

备注(2):What was surprising  us 为融合性关系代词what引导的名词性关系分句作主句的主语，即主语从句。（what=the thing that）what在主语从句作主语。

备注(3):(that省略) the biggest predictor was not whether they had exerted self-control .为从属连词that引导的表语从句。The biggest predictor为表语从句主语，wasn’t为系动词否定结构，whether they had exerted self-control .为that表语从句的表语，这个表语也是由连词whether引导表语从句。

总结：以下三个句子都是正确的。第1个句子中的surprising为分词形容词用法，第2个句子中的surprising为及物动词surprise的现在分词形式，第3个句子结构为及物动词surprise的过去式surprised。

【1】What is surprising to sb is +表语  对某人来说是出人意料的事情是......【正确】

What was surprising to us was(that省略) the biggest predictor was not whether they had exerted self-control .

【2】What is surprising sb is +表语    正在使某人感到意外的事情是.....【正确】

What was surprising us was(that省略) the biggest predictor was not whether they had exerted self-control .

【3】What surprised sb is +表语    使某人感到意外的事情是.....【正确】

What surprised us was(that省略) the biggest predictor was not whether they had exerted self-control .