whose book do you think is this?你觉得这是谁的书?
on time 是按时,准时的意思,in time 是及时的意思到底你们俩谁的对啊whose book do you think is this?这个对，这个是纯正的英语说法Do you think whose book this is.对吗？Do you think whose book this is.错的一塌糊涂，whose book is this？do you think 是作为插入语的。所以whose book do you think is this?