There are two ways to look at this question {#blank#}1{#/blank#}relating to eggs in general or to the chicken egg specifically. Either way, the answer is the same: the egg came before the chicken.{#blank#}2{#/blank#} the case of eggs in general, animals such as dinosaurs were laying eggs long before the modern chicken came into existence,{#blank#}3{#/blank#} (mean) that in this sense, the egg predated (早于) the chicken by thousands of years. As for the chicken egg specifically , according to NPR's Robert Krulwich, the modern chicken{#blank#}4{#/blank#} (hatch 孵化) from an egg, meaning the egg came first.

    The key to understanding the answer, and indeed the question itself, is to understand what the question is getting at. The dilemma is to understand {#blank#}5{#/blank#} a chicken-like bird transformed into{#blank#}6{#/blank#} is known as a modern chicken after being hatched or whether two chicken-like birds {#blank#}7{#/blank#} (lay) and fertilized an egg that then hatched a fully formed chicken. In this case, the latter option is the most realistic, therefore answering the question of which came first.{#blank#}8{#/blank#} (essential), a bird that was similar to a hen and another bird that is similar to {#blank#}9{#/blank#} rooster combined their genetic material, leading to a gene mutation (突变) that resulted in the chicken that is{#blank#}10{#/blank#}(good) known and loved today.

    My friend had a chance to make a trip to Hong Kong {#blank#}1{#/blank#} August 15, 2011. He had dreamed about {#blank#}2{#/blank#} (visit) it since his boyhood and it {#blank#}3{#/blank#} (be) the first time that he had been there. The following was {#blank#}4{#/blank#} he had seen.

    Arriving there, he was {#blank#}5{#/blank#} (impress) by its beautiful scenery and tall buildings. It is said that Hong Kong has the most skyscrapers in the world. Wherever he went, he saw many smiling {#blank#}6{#/blank#} (face) there. People in Hong Kong were kind, generous, easygoing and ready to help others. Much to {#blank#}7{#/blank#}（he）surprise, he saw that people there always kept order in public places. {#blank#}8{#/blank#} crowds of people were waiting for the next train at the subway station, they were talking in such a low voice as not to disturb one another.

    Chinese and English are their official languages. English is {#blank#}9{#/blank#} (wide) used in governments, markets, service centers and other fields.

    Staying there for only a week was a good experience {#blank#}10{#/blank#} he will never forget

    Many people living in cities see riding a bicycle as good exercise. But, a recent medical {#blank#}1{#/blank#} research warned that cyclists should think twice before cycling in the streets: it actually does more harm than good {#blank#}2{#/blank#} their bodies.

    Is cycling in cities really bad for your health? Probably yes. The main danger comes from the air around you. Breathing {#blank#}3{#/blank#} in air pollution from taxis and buses can damage blood vessels(血管).Scientists say the damage could outweigh the health benefits of cycling.

    David Newby, a British {#blank#}4{#/blank#} researcher at Edinburgh University broke the news. In his tests, 15 healthy men cycled {#blank#}5{#/blank#} on exercise bikes in a room with levels of air pollution similar to those found {#blank#}6{#/blank#} on a crowded city street. After an hour of cycling, the scientists found their blood vessels became less flexible and produced less of a protein(蛋白质){#blank#}7{#/blank#} the heart needs. The damage leads to the early stages of heart disease. What's worse, the faster a cyclist pedals (蹬车),{#blank#}8{#/blank#} more air they breathe in. So those who believe {#blank#}9{#/blank#} they are improving their fitness the most are storing up the biggest trouble for {#blank#}10{#/blank#}.

    We've all turned to sad music to make us feel {#blank#}1{#/blank#} (good)at some point in our lives, but why does doubling down on the sadness help drag us out of the mire(泥沼)？

    A new study sheds light on what's going on inside our brains {#blank#}2{#/blank#}we match our music to our feelings. It looks like sad music can be enjoyable -rather than {#blank#}3{#/blank#}(simple) depressing- because it triggers positive memories that can help to lift our mood. Psychologist Adrian North from Curtin University in Australia says there {#blank#}4{#/blank#} (be)two groups of possible{#blank#}5{#/blank#} (explain)for why we enjoy listening to sad music like this: one from social psychology, and one from cognitive neuroscience(认知神经学).

    In terms of social psychology, one way of {#blank#}6{#/blank#}(think) about this is that we feel much better about {#blank#}7{#/blank#} (we) if we focus on someone who's doing even worse, a process known as downward social comparison. Everything's going to be okay, because this person {#blank#}8{#/blank#}(have) an even worse day than you are.

    Another theory from social psychology is that people like to listen {#blank#}9{#/blank#} music that mirrors the tone of their current life circumstances -the songs act as {#blank#}10{#/blank#}sort of tuning fork(音叉) for our own situations and they resonate(共鸣) with us