如图，⊙O的直径CD过弦EF的中点G，∠EOD＝40°，则∠DCF=____．

      useful advice he has given us !

肺的结构与呼吸功能相适应，与此无关的叙述是（    ）

1.What are your best ____(祝愿)?

2.Their ____ (工作) are standing and watching at the door.

3.My friends are coming ____(不久).

4.He____ (听) to the teachers carefully in class.

5.My friend ____(写信) to me three times a month.

无机盐约占人体重的