Match the underlined part of each sentence (a-d) with the correct meaning a) I can arrive at any time. It's necessary for me to
b) I can't wear jeans. It isn't OK for me to
e) I have to use a computer. It isn't necessary for me to
d) I don't have to wear a uniform. It's OK for me to
1 The internal combustion engine is called so because fuel is burned
directly inside the engine itself
2 To describe the complete cycle, let's that the piston is
the top of the stroke (top dead center) and the and the exhaust
valves are closed, When the piston
moves down the inlet valve opens to
intake a charge of fuel into the cylinder. This is called the inlet (intake)
stroke.
3 On reaching the lowest position (bottom dead center) the pis-
der,
begins move upward the closed upper part the cylinder,
the valve is closed and the mixture is compressed by the rising
piston. This is called the compression stroke.
4 Asthe piston again
the top dead center the spark plugs ignite the mixture, hoth valves he
ing closed during its combustion. As a result of burning mixtures the
gases expand and great pressure makes the piston move back down the
cylinder. This stroke is called the
reaches
powerstroke
5 When the piston reach
the bottom of its stroke, the exhaust valve is opened, pressure is re-
lensed, and the piston again rises. It lets the burnt gas flow through the
exhaust valve into the atmosphere. This is called thexhaust stroke
which completes the cycle
6 So the piston moves in the cylinder down
(intakestroke), up (compression stroke), down (powerstroke), up (ex-
hanst stroke)
1 a
2 a
3 b
4 a
5 b
6 a
Объяснение: