题目

“酒是陈的香”，是因为酒在储存过程中生成了有香味的乙酸乙酯。在实验室我们可以用如图所示的装置来制取乙酸乙酯。回答下列问题： （1）写出试管a中发生的化学方程式：                                         。 试管b中所盛的溶液为               ， 其主要作用是 ___________________________。 试管b中的导管要在液面的稍上方，不能插入液面以下，其目的是_____________________ 。 该实验中，若用3mol乙醇和1mol乙酸 在浓硫酸CYellowstone WeatherYellowstone National Park is at high altitude. Most of the park is above 7500 feet (2275 meters).Yellowstone’s weather is unpredictable. In summer, it may be warm and sunny with temperatures in the high 70s. At night in any given month, the temperature may drop close to freezing. So it is best to come prepared for cold evenings and mornings, especially if you are camping or hiking. When you leave your campsite, please leave it prepared for possible thundershowers and wind.A sunny warm day may become fiercely stormy with wind, rain, sleet and sometimes snow. Without enough clothing, an easy day hike or boat trip can turn into a battle for survival.Seasonal Weather InformationSpringCold and snow continue into May, althoughtemperatures gradually climb. Early in spring, daytime temperatures average in the 40s to 50s; by late May and June, they may reach the 60s and 70s. Nighttime lows fall below freezing.   SummerDaytime temperatures are usually in the 70s, occasionally reaching the 80s in the lower area. Nights are cool, temperatures may drop in the 40s and 30s，sometimes even the 20s. June can be cool and rainy; July and August tend to be somewhat drier, although afternoon thundershowers are common.FallWeather can be pleasant, although temperatures average 10~20 degrees lower than summer readings. Nighttime lows can fall into the teens and even lower. Snowstorms increase in frequency as the weeks go by or towards the end of the fall season. WinterTemperatures often stay near zero throughout the day, occasionally reaching high in the 20s. Subzero nighttime lows are common. Annual snowfall averages nearly 150 inches in most of the park. At higher places, 200~400 inches of snow have been recorded.64、The theme（主题）of this passage is       in Yellowstone National Park.A、the special weather      B、the beautiful sceneryC、campsites for free       D、terrible thunderstorms65、This passage is mainly written for those who plan to     in Yellowstone National Park.A、do research work       B、take a business trip C、have sports games      D、spend their holidays or take a tour66、Which of the following best describes Yellowstone’s weather?A、The weather is generally changeable and it snows most of the year.B、The lowest nighttime temperature often stays about zero in winter.C、Weather in fall is pleasant and temperatures never fall below freezing.D、It’s pretty warm in the day and very cold at night throughout the year.67、If you are planning to spend your holiday in Yellowstone National Park in summer, what should you take with you?A、Just some light clothing such as T-shirts or skirts.B、Just some warm clothing such as sweaters or coats.C、Both light clothing and warm clothing.  D、Either light clothing or warm clothing.