问题 单项选择题

有一个摆地摊的摊主,他拿出3个白球,3个黑球,放在一个袋子里,让人们摸球中奖。只需2元就可以从袋子里摸3个球,如果摸到的3个球都是白球,可得10元回扣,那么中奖的概率是多少如果一天有300人摸奖,摊主能骗走多少元()

A.1/40,350

B.1/20,450

C.1/30,420

D.1/10,450

答案

参考答案:B

解析:

6个球当中摸3个球有种情况,即20种情况,而摸3个都是白球只是其中的一种情况,即摸中的概率为;300人摸奖摊主能骗去的钱为元,故选B。

完形填空
完形填空。

     In the USA, Mother's Day is a holiday on the    1    Sunday in May. On that day    2    give their mother
cards, presents and flowers. One of the best    3    to celebrate Mother's Day is    4    your mother a day off
(休息一天). Let her have a good rest    5    other members of the family do the housework.
      Many families begin Mother's Day    6    breakfast in bed. Usually dad and the children will let mom    7  
 more as they go into    8    and get ready for her favorite meal.    9    the food is cooked, they keep everything
nice on a plate. They don't forget    10    the bottle with only one flower on the plate. Then dad and children
carefully carry the plate to mom's bedroom.
      Many families take mom to her favorite restaurant for a meal. It is a good day to let your mom have a
rest and let her see what a wonderful family she has.

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多项选择题