An American game that has traveled well is basketball.     1     is now played by more than 250 million people worldwide in an     2     (organize) way, as well as by countless others in informal games. Basketball began in 1891, when a minister,     3     (call) James Naismith, was asked to teach a class of young men in Springfield, Massachusetts.

The class was known     4     being difficult to teach and Naismith was told to invent a new game     5     (keep) the young men busy. Then it was winter and very cold outside. It needed to be a game that could be played indoors.

Naismith    6    (think) back to his childhood in Canada where he and his friends had played a game which had involved (需要) trying to hit     7     big stone off a rock with smaller stones. He also remembered     8     (watch) rugby players throw a ball into a box or fruit basket     9     had been raised up. Naismith made up the     10     (rule) for the game in less than an hour. Most of them still apply in some form today.

According to a new review of research about good mood(心情）and physical activity,people who exercise even once a week or for as little as 10 minutes a day tends to be more cheerful than those who never exercise.And any type of exercise may be     1     （help).

The idea       2    moving can affect our mood is not new.A number of past studies have noted that       3    （physical)active people have much       4    （low)risks of developing depression and anxiety.But fewer past studies explored links between physical activity and positive feelings,especially in people who already were psychologically healthy.

So for the new review     5    （publish)in the Journal of Happiness Studies,researchers at the University of Michigan decided to collect and     6    （analysis)multiple past studies on 99 exercising and happiness. They     7    (begin)by searching through research databases for relevant studies.And for most of them,the Michigan researchers found exercise was strongly linked to happiness.The type of exercise did not seem     8    （matter).Some happy people walked or jogged.     9     practiced yoga-style movements and stretching.And       10    amount of exercise needed to influence happiness was slight.But more movement generally contributed to greater happiness.

More than half of former host cities for the Winter Olympics will be too hot    1    (deal)with such games by the end of this century. That is the prediction of a recent study.

It's not just the Olympics that    2    (be) at risk now. “The world of winter sports is changing as the global climate continues warming,”says Daniel Scott,    3    climate-change researcher in Canada. He led a team of researchers,    4    used math to predict how winter conditions will have changed by February 2050 and 2080. February is the month when the Olympic winter games are    5    (typical) played．

Scott and his team forecast temperatures and snow cover for the 19 cities that have already hosted Winter Olympics, and two    6    (addition) cities: PyeongChang, South Korea，and Beijing, China, where the 2022 Winter Olympics will be held.

Scott’s team    7    (start) with looking at historic winter conditions, and then used computer models to predict conditions in the future.    8    ( they) model predicted that by2050，the average February temperatures in past Winter Olympic host cities will rise by 1.9     9    2.1 degrees Celsius. These temperatures can affect the quality of snow, thus    10    （increase)the chance of accidents.