青少年若不注意用眼卫生会容易造成近视，一旦是真性近视了，应佩戴什么镜加以矫正？（　　）

    Did you know that badminton is also a fast-paced competitive sport? Badminton has been a Summer Olympic sport since 1992. Para-badminton will be included in the 2020 Summer Olympic Games in Tokyo. Here's what you need to know if your child is interested in badminton.

    Badminton is played on a 44-foot-long rectangular (矩形的) court that is 17 feet wide for singles and 20 feet wide for doubles. It is divided in the middle by a net placed 5 feet off the ground, like volleyball, not at ground level like tennis.

In competition, each match is a set of three games played to 21 points. There is a one-minute break when a player or team reaches 11 points, and a two-minute break in between the first and second games and the second and third games.

Age kids can start: About 6 years old.

    Best for kids who: Have good skills, are patient and hardworking, and can handle the pressure of one-on-one or two-on-two competition.

Team or individual: Matches can be singles (one-on-one) or doubles (two-on-two).

    Fun fact: Badminton is the only sport that has mixed doubles event in the Olympic Games.

    Costs: Beginners are expected to pay $30 to $40 for an entry-level racquet (球拍). Badminton shoes are similar in price to other athletic shoes. Join a club or team for lessons. A one-hour group lesson for beginners should cost $20 to $25, with costs increasing as your child moves up the ranks. You will also pay entry fees for competitions.

    Time commitment required: Beginners will play for just an hour or two per week.

    Potential for injury: Players have a very low risk of injury. Players who wear glasses should use eye protection.

外贸所得在宋朝的财政收入中占有重要地位。为鼓励海外贸易，宋朝政府在主要港口设立的管理机构是（    ）       

某兴趣小组同学准备进行常见酸、碱、盐的性质实验时，发现实验台上摆放的药品中（如图1），有一装溶液的试剂瓶未盖瓶盖且标签破损，于是决定对这瓶溶液进行实验探究：

【提出问题】这瓶溶液是什么溶液？

【获得信息】实验中用到含有钠元素的物质是氯化钠、氢氧化钠、碳酸钠

【提出猜想】这瓶溶液原来是：

猜想一：氯化钠溶液；   猜想二：氢氧化钠溶液；   猜想三：碳酸钠溶液．

    If Frida Kahlo（1907-1954） is today one of the best-known and most popular figures of 20th-century, Mexican art, it is undoubtedly because of her personality and the originality（独创性）of a body of works. Her work is, above all, the expression of a real life－a tragic and stormy life, one that challenged all conventions. The mere mention of her name excites enthusiasm and admiration, but her work is rarely exhibited, and has not been shown in France for fifteen years. The selection to go on show at the Musee de L'Orangerie includes major works by the artist, with masterpieces from the Museo Dolores Olmedo.

    The life and work of Frida Kahlo cannot be separated from those of her companion Diego Rivera（1886-1957）. Together they became figures of legend, and both have a place in the pantheon of 20th-century Mexican artists. Famous for his large wall paintings, Rivera's easel paintings, drawings and prints, which form a large part of his artistic production, are less well-known to the public in Europe. The exhibition aims to trace his artistic career from the early Cubist images, revealing his links with the Paris artists whose works are a key element in the Orangerie collections, to the paintings that established him as the founder of the 20th-century school of Mexican art. His travels throughout Europe influenced his vision and his skills without ever distancing him from his roots, thus confirming his place in history as the founder of the nationalist school.

    The exhibition devoted to the legendary couple Diego Rivera and Frida Kahlo presents their works together, as if to confirm the impossibility of their divorce that was in fact finalized（定下来）but reconsidered after just one year apart. It also gives us a better view of their respective artistic worlds, so different and yet so complementary（互补的）, through the deep-rooted attachment they shared to their country.