在棱长为1的正方体ABCD﹣A₁B₁C₁D₁中，M和N分别为A₁B₁和BB₁的中点，那么直线AM与CN所成角的余弦值是（  ）

①接受现实，学会欣赏自己                     ②学会欣赏自己的独特，欣赏自己的优点

③学会以积极心态接纳自己的形象         ④整容非常有必要，能使自己变得更美丽

下列所列的四个比例尺中最小的是（     ）

    Plants are very important. This is because plants can make food from air, water and sunlight. Animals and man cannot make food from air, water and sunlight. Animals can get their food by eating plants and other animals. Man gets his food by eating plants and animals, too. So animals and man need plants to live. This is why there are so many plants around us.
    There are two kinds of plants: flowering plants and non-flowering(无花) plants. Almost all the trees around us are flowers and fruit. Non-flowering plants don't grow flowers. You can't see many non-flowering plants around you.
    If you look carefully at the plants around you, you'll find that there are many kinds of plants. Some plants are very big and some very small. Most of them are green. We can live on the earth because of the plants around us.