题干

一个盒子中装有4张卡片,每张卡片上写有1个数字,数字分别是1,2,3,4,现从盒子中随机抽取卡片,回答下列问题:(1)若一次从中随机抽取3张卡片,求3张卡片上数字之和大于或等于7的概率;(2)若第一次随机抽取1张卡片,放回后再随机抽取1张卡片,求两次抽取的卡片中至少一次抽到数字2的概率

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Dear Liz,

    My stay in Thailand has certainly been the experience of my life.

    Life is busy and exciting.Bangkok is just like any other big city with a population of 10  million and heavy traffic.I'm very lucky because my host family is in a nice quiet area outside the city.There are Mr. and Mrs. Phairat, their son Sanan, who is 18, the daughter Chinda, who is 16, and Grandpa and Grandma.

    I go to an international school with Sanan and Chinda.The school teaches about 70 percent in English,and 30 percent in Thai. I've learned some spoken language,but Thai writing is very difficult.The cooking lesson is my favourite.I'm learning all about Thai food and culture People don't use chopsticks here,but spoons and forks.When I come back,I'm going to cook you a real Thai meal.

    Last weekend we visited some temples.We also drove to Pattaya beach near Bangkok.I thought it was great,but Sanan and Chinda say that next month they're taking me to Phuket  Island,where the beaches are even more beautiful.The month after next,we're going to travel to Mr.Phairat's hometown in the north of Thailand.The Phairats own land there,and they have two elephants.I'm going to ride those elephants — and even wash them.Sanan and  Chinda say it's really fun.I'm amazed by everything in this country,especially by the elephants.Elephants are an  important pan of Thai culture and way of life.They have been a traditional symbol(象征)of Thailand for many years in times of war and peace.In the seventh century,a Thai king trained 20,000 elephants for battle.

    I'll tell you all about my Thai boxing(拳击)lessons next time I write.

Love,

Mandy