insist作及物动词时后面是不是必须加that?

nsist 用法与suggest 相似.insist作“坚持”说时,要用陈述语气；作“坚决主张；坚决要求”讲时,用虚拟语气.如：
When the son suggested that they should go to the park on Sunday, the expression on his father’s face suggested that he agreed with him.
当儿子提议星期天去公园时,父亲用表情表示了默许.
They insisted that he （should）be present at the ceremony.
他们坚决要求他出席这次典礼.
He insisted that he was innocent.=He insisted on his innocence.
他坚持说自己是无辜的.
因为这个词的意思觉得,做及物动词时候
insist that 的情况比较多举个不用that的例子Diehard optimists might insist not.顽固的乐观派可能坚称不会Mr king will insist he is no empire-builder.金先生将坚称他不是王国缔造者。that省略that什么情况下可省略，还有insist后面是不是不一定加从句，也可以加词吧？真的不用追根究底的只要记住一般都是that就行了