用所给单词的适当形式填空。

1. We need to produce a lot of             _ (medical) to save those people who get HINI flu.

2. More and more parents are _          _ (worry) about their children playing computer games.

3. As a student, you should learn more            _ (know) from your teachers.

4. All the land was            _ (cover) by the white snow when we got up last Sunday.

5. I think playing computer games is not _            (help) to your study.

关于左心房增大的X线表现描述恰当的是

A．心左缘双弧影，心底部双心房影
B．食管向前受压移位
C．心左缘可见左心耳突出(第三弓)
D．左主支气管受压降低
E．以上都不是