A．To introduce a way to improve early children reading.
B．To overcome primary school pupils' reading difficulty.
C．To encourage the publication of more children's books.
D．To remind children of the importance of reading for fun.
A．The orbits of comets.
B．The structure of comets.
C．The origin and life cycle of comets.
D．Unique characteristics of a famous comet.
A．To account for the comet's composition of ice and dust.
B．To show the effect of Jupiter's gravity on the comet's orbit.
C．To explain why the comet is not visible from Earth very often.
D．To argue that the comet's orbit should not be considered periodic.
A．It moves slower.
B．It starts to heat up.
C．It loses some material.
D．It absorbs gases from the Sun.