题干

爆米花是将玉米放入铁锅内,边加热边翻动一段时间后,“砰”的一声变成了玉米花.下列说法正确的是(   )

A:玉米粒主要通过翻动铁锅对其做功,使其内能增加

B:玉米粒主要通过与铁锅间的热传递,使其内能增加

C:玉米粒内水份受热膨胀对粒壳做功爆开,水分内能不变

D:玉米粒内水份受热膨胀,粒壳爆开,对外做功,玉米粒内能增加

上一题 下一题 0.0难度 选择题 更新时间:2014-12-14 08:13:36

答案(点此获取答案解析)

B

同类题1

阅读与回答问题

    Sixteen is a special age in the United States. There's often a special celebration for a girl's 16th birthday---a big party called Sweet-16. It is like a wedding reception(结婚晚宴) in the number of guests and gifts handed out.

    About a month before the party, the girl's family sends out invitations to the guests. They must buy a special present for the birthday girl and the girl guests find good dresses to wear. A sweet-16 present usually costs $40 to $60. This is about $20 more than the usual-cost of a birthday present.

    The party itself is not held at someone's house. The hostess rents(租赁) a reception hall for the event. Food, cake and a DJ are provided. Around 6'clock, guests arrive and meet the birthday girl. Then the girl and her father have a special father-daughter dance. After that, guests dance for about 30 to 45 minutes.

    Then there is the most important part of the Sweet-16 party, the candle-lighting ceremony.

    The sweet-16 hostess stands behind 16 unlit(未点燃的) candles and dedicates(献给) each candle to her friends, family, and anything that she feels is important to her. A lot of crying and hugging goes on at this time.

    Afterwards, people sit and eat. Most guests begin leaving around 11 o'clock.

    This school year, I have been to two Sweet-16s. I am one of the youngest students in my grade (My birthday is in December). I'll have to wait another year before I can have my own special Sweet-16 party. I can't wait for it!