2. Join the parts of the sentences using when or while Example: She / swim / she / lose / her hat. (when)
She was swimming when she lost her hat.
I / do / my homework / somebody / come / in the room. (while)


Susan / drive / fast / she / have / an accident. (when)

The children / play / football / it / start / to rain (while)

We / watch / TV / the lights / go out (when)

While I was doing my homework, somebody came into the room.  

Susan was driving fast when she had an accident.  

While the children were playing football, it started to rain.  

We were watching TV when the lights went out.

Объяснение:

While I was doing my homework, somebody came into the room.

While the children were playing football, it started to rain.

Если мы говорим, что одно действие было, образно выражаясь, в разгаре, когда произошло другое - короткое - действие, мы употребляем в придаточном предложении союз while. Действие, которое было "в разгаре", передается временем Continuous, короткое -  временем группы Simple.

We were watching TV when the lights went out.

Susan was driving fast when she had an accident.

Мы употребляем в придаточном предложении союз when, когда говорим, что одно короткое действие прерывает  другое действие, находившееся в процессе совершения какое-то время. В таких случаях длительное действие передается глаголом в Continuous, короткое -  глаголом в Simple.