...aughing 和 We sang and danced 是并列句(compound sentence)，而不是简单句(simple sentence)包含并列谓语(compound predicate)，其中的原因牵涉到并列句句子成分的省略(omission of words as understood)，如主语省略(ellipsis of the subject)等。
The main clause and subordinate clause of compound sentence must have subject and predicate, as same as the simple sentence.
复合句的主句和从句也和简单句一样，必须有主语和谓语。
2
The main clause and subordinate clause of compound sentence must have subject and predicate as same as the simple sentence.
复合句的主句和从句也和简单句一样，必须有主语和谓语。
3
The reason which leads to the asymmetry is that these nouns experienced changes from predicate-object verbal phrase to predicate-object compound noun in their construction process.