The two diagrams illustrate the main parts of a hot air balloon and indicate how it ascends and descends in flight.

The 2 graphs depict the different parts of a

balloon

and how it can ascend or descend during the flight.

Overall

,

it is clear that

to make the

balloon

ascend, the

gas

burners have to be on , in order to make the hot air go up in the

balloon

's

envelope

and the

valve

has to be closed,

while

the

gas

has to be off and the

valve

has to be opened to let go the hot air to make the

balloon

descend. The

balloon

's ascent is made thanks to the

envelope

which ends with a

valve

, which has to be closed to make the

balloon

go up.

In addition

, the

gas

tanks, which are inside the basket for passengers, have to be

open

Wrong verb form

opened

show examples

in order to inflate the

balloon

's

envelope

. In opposition, the ballon's descent can be made thanks to the opening of the

valve

situated on the top of the

envelope

.

Then

, the

gas

tanks have to be closed and the burners off to stop the hot air making.

Additionally

, the

valve

of the

balloon

has to be opened by the

valve

cord activated by the pilot .