回答如下:
1.
非谓语动词是指由动词变化而成,仍具有动词的性质与意义,但不能作为动词使用的词。它通常有三种形式:
不定式,动名词和分词。
2. 非谓语动词与谓语动词的区别是:非谓语动词在句中不能用作谓语,只能作主语、
表语、定语、状语、宾语、同位语、宾补行为动词。
系动词、助动词、情态动词都不能单独作谓语,其复合谓语结构是:系动词+表语;助动词、情态动词+动词原形或其他动词形式。如:
He is ill / in the room / a doctor.
They can swim.
It is raining hard.
He has gone to Beijing.
He does know it.
He must have been late yesterday.