用所给词的适当形式填空。

1. -Have you          (find) your knife yet?

    -Not yet.

2. -When you         (come) back?

    -An hour ago.

3.  We can see some children          (play) games now.

4. -         you         (write)a letter to your aunt yet?

    -No, I         .I        (write)it next week.

5.           they       (see) the teacher just now?

______是学校教育中最基本的活动，不仅是智育的主要途径，也是德育、体育、美育等的基本途径。