What work can one never finish?

In the picture given below, can you find out which digit will take place of the question mark?

A doctor and a boy were fishing. The boy was the doctor’s son, but the doctor was not the boy’s father. Who was the doctor?

John was running from 40 thieves. John has got 3 gold boxes which weigh as 4kg, 2kg, and 1kg respectively. A witty man asked John to stay with him for seven days in exchange for 1kg gold per day. John needs to stay there for seven days and also do not want to give the witty man any advance. How can John pay for his seven days stay?

In a classic wine shop, the list of three most popular wines are:
- The cost of 1 French wine bottle: 500$
- The cost of 1 German wine bottle: 100$
- The cost of 20 Dutch wine bottles: 100$

John entered the wine shop and he needs to buy
- All three types of wine bottles.
- Needs to buy Dutch wine bottles in multiples of 20.
- Need to buy 100 wine bottles in total.

John has only 10000$. How many wine bottles of each type, John must buy?

Who always enjoys poor health?

In a football game, Christina defeated Teresa by 2 - 0 but no man from either side scored. How can this be possible?

Replace all '*' with digits 1, 2, 3, 4, 5 and 6 to make below statement true.

* *
x *
=====
* * *

4 fathers, 2 grand-fathers and 4 sons went to watch the movie.What is the minimum number of tickets they need to buy ?

Cristina leaves home and then she makes exactly 3 left turns and returns home where she found 2 girls wearing the mask.

Who are these two masked girls?