具备下列哪一特征的植物不适宜生活在如图所示生物生活的环境中（　　）

下列关于藻类、苔藓、蕨类植物的叙述正确的是（    ）

利用定积分的几何意义，计算： $\int {}_1^2\sqrt{4-x^2}dx$ ＝____.

   Jane always goes to school early. She likes to talk to her friends before class. After school she does not go home early. She is always late. Jane stops to see the animals in the pet shop. She likes to see the dogs. One of them is a little white dog. She watches the little dog play in the window of the shop. She watches for a long time, so she comes home late.
   One day her father and mother ask why she is late, and she tells them about the little dog in the pet shop.
   Jane is not late the next day. She stops to look in the window of the shop. But she doesn’t see the dog, and she is very sad. She is also very happy, today is her birthday.
   Mother shows her a big birthday cake and Father gives her a birthday surprise(惊奇). He gives her the little white dog from the shop. Jane is very happy. The next day Jane does not come home late. She runs home to play with the white dog.

下列气候类型，主要分布在大陆内部的是（　　）