请将下列句子改为同义句，每空一词。

1. It's time for lunch.

    It's time                         lunch.

2. I had a great time in Beijing.

    I                         in Beijing.

3. We would like to buy some food.

    We                          buy some food.

4. Beijing is not near our city.

    Beijing is                          our city.

5. The student likes to walk to school.

    The student likes to go to school                         .

6. My father bought me a computer yesterday.

    My father bought a                         me yesterday.

7. Let's show the way to you.

    Let's show             the             .

8. I'm very tired and can't walk home.

    I'm             tired              walk home.

9. A plane is faster than a train.

    A train is             than a            .

10. I want to send a letter to her.

      I want to send                         letter.

成人体内约含钙1.2kg，其中99%存在于骨骼和牙齿中．在元素周期表中，钙元素的某些信息如图所示．下列说法不正确的是（　　）

A．钙原子的核外电子数为20

B．钙原子的原子序数为20

C．该元素在地壳中的含量为40.08%

D．该元素属于金属元素