5．The word"day"has two meanings．When we talk about the number of days in a year，we are using"day"to mean 24hours．But when we talk about day and night，we are using"day"to mean the time between sunrise and sunset．Because the earth looks like a ball，the sun can shine on only half of it at a time．Always one half of the earth is having day and the other half night．At the equator （赤道）day and night are sometimes the same length．They are each twelve hours long．The sun rises at 6o'clock in the morning and sets at 6o'clock in the evening．For six months the North Pole is tilted （傾斜的）toward the sun．In those months the Northern Hemisphere gets more hours of sunlight than the southern Hemisphere．Days are longer than nights．South of the equator nights are longer than days．For the other six months the North Pole is tilted away from the sun．Then the Southern Hemisphere gets more sunlight．Days are longer than nights．North of the equator nights are longer than days．Winter is the season of long nights．Summer is the season of long days．
76．According to the passage，the"day"meansC．
A.24hours B．sunrise C．both A and D D．the time between sunrise and sunset
77．At the equator day is as long as nightB．A．usually B．sometimes C．never D．a(chǎn)lways
78．What is the Chinese meaning of the underlined word Hemisphere？A
A．半球B．地殼C．極地 D．地軸
79．When the Western Hemisphere is having day，the Eastern Hemisphere is havingD．
A．both day and night B．day C．neither day nor night D．night
80．Which of the following statements is TRUE？A
A．When the Southern Hemisphere gets more sunlight，days are longer than nights．
B．Winter is the season of long days．C．Summer is the season of short days．
D．When the Southern Hemisphere gets more sunlight，days are shorter than night．
