题干

在“噬菌体侵染细菌”的实验中,若使放射性同位素主要分布在离心管的沉淀物中,则获得侵染噬菌体的方法是[   ]

A:用含35S的培养基直接培养噬菌体

B:用含32P的培养基直接培养噬菌体

C:用含35S的培养基培养细菌,再用此细菌培养噬菌体

D:用含32P的培养基培养细菌,再用此细菌培养噬菌体

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D

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    La Tomatina, Spain

    Tomato juice flows through the streets of Bunol on the last Wednesday of August as the worlds largest tomato fight happens. Festivities begin in the town square where there is a huge pole covered in soap and with a leg of ham at the top. Participants try to climb up the pole to get the ham as watchers throw buckets of water to them. After a gun is fired to signal the beginning of the fight, people catch the tomatoes and throw each other in the streets until the gun sounds again, marking the end of the event.

    Holi, India

    This spring festival is celebrated throughout the country in late February or early March. The two-day event celebrates the legend of Prahlad, who escaped unharmed from the fire of the evil Holika Dahan. People mark the event by lighting fires and throwing colored powder on one another Children load colored water into toy pistols called pichkari and take aim at passers-by. Holi is known as a happy celebration of the victory of good over evil.

    Burning Man, Nevada

    This infamous festival began in 1986 with the burning of a large figure to mark the summer solstice (夏至). It's since grown into a week-long annual event that draws more than 48,000 people to the Black Rock Dessert. It is held during the week before Labor Day. Participants set up camp in the desert to celebrate art.

    Songkran, Thailand

    This festival marks the Thai New Year, which is celebrated in the second week of April. This is the hottest time of the year in Thailand, so it makes sense that the biggest Songkran tradition is to throw water on people. Thais of all ages join in water fights, using buckets, hoses (软管) and water guns to celebrate the event.