质量为2kg的物体A以5m/s的速度向北运动，另一个质量为0.5kg的物体B以10m/s的速度向西运动，则E_kA____E_kB （填=；＞；＜；）

化简：（﹣$\frac{y}{x^2}$）³÷（$\frac{y^2}{x^3}$•$\frac{x^2}{y}$）=____ 

如图表示反射和反射弧，下列说法正确的是（　　）

下列物质中不能发生消去反应的是                               （   ）

在方框中填入一个恰当的词、或填入所给单词的适当形式，使短文通顺、正确、连贯。
    A lot of people wish to be slim, but at the same time they are____（worry）about their health. In fact, it is important for everyone to lose weight healthily. A strong body can keep you working in a high speed and make you more positive every day. However, how can you do it? Here's some good____（advice）.
    ●Drink plenty of water and eat____healthy diet. If you feel like____（eat）snacks, drink a glass of water first. If you are still hungry after 15____（minute）, then it's time for a light snack. Try to stay away from food with high calories, such as sweets and fast food.
    ●Do not eat____(much) than you can consume (消耗). People get fat because they can’t consume all the calories ____they get. So, knowing how many calories you really need is very important.
    ●Take enough exercise.  The  “333” is good   for you—exercise three____(time) a week, for at least 30 minutes at a time, and your pulse rate (脉搏率) should be more than 130 after____(exercise).
    Keep the three pieces of advice in mind and follow the advice. Then you'll____(sure) have a slim and strong body.