Tom is riding his bike isn't he?如果是表示肯定说Tom是在骑自行车那么是说yes还是no

这种问题,你只要看前面的部分,Tom is riding his bike,你不要管后面是什么,前面该怎么回答就怎么回答.如果有不会,可以追问
反义疑问句(The Disjunctive Question)
即附加疑问句.它表示提问人的看法,没有把握,需要对方证实.
它表示提问人的看法,没有把握,需要对方证实.反义疑问句由两部分组成：前一部分是一个陈述句,后一部分是一个简短的疑问句,两部分的人称时态应保持一致.
1．陈述部分肯定式+疑问部分否定式
2．陈述部分否定式+疑问部分肯定式
They work hare, don’t they?
She was ill yesterday, wasn’t she?
You didn’t go, did you?
He can’t ride a bike, can he?
请注意以下句型的反义疑问句的用法：
1．当陈述部分的主语是I , everyone, everything, nobody 时,后面的疑问句应表示为：
I am a student, aren’t I
Everyone is in the classroom, aren’t they?
Everything begins to grow in spring, doesn’t it?
Nobody will go, will they?
2. 当陈述部分有never,seldom, hardly,few,little,barely, scarcely, nothing 等否定词时,后面的疑问句则表示为：
There are few apples in the basket, are there?
He can hardly swim, can he?
They seldom come late, do they?
3. 当陈述部分是I think 加从句时,疑问句应和从句的人称时态保持一致.
I think chickens can swim, can’t they?
I think Lucy is a good girl, isn’t she?
I didn't think he was happy, was he?
4. 陈述部分有had better 时,疑问句应用hadn’t开头：
you’d better get up early, hadn’t you?
5.当陈述部分是祈使句时,疑问句要根据语气来表达
Let’s go out for a walk, shall we?
Let us go our for a walk, will you?
Turn on the radio, will you?
6.反义疑问句的回答用yes, no, 但是,当陈述部分是否定形式时,回答要按事实.如：
They don’t work hard, do they? 他们不太努力工作,是吗?
Yes, they do. 不,他们工作努力./No, they don’t. 对, 他们工作不努力.

回答时，需要表达的意思是肯定的，就需要用yes;若是否定的，则需要用no
所以，肯定说Tom是在骑自行车那么是 Yes, he is.

yes,he is.
这种反义疑问句说英语汉语对照会很容易迷糊，其实有条很简单的原则，汉语意思为 是就yes，不是就no.