1. When I was a teenager, I felt that I was just young and uncertain----that I was a new boy in a huge school.
    我十几岁时，总感到自己年轻，有些事拿不准 -- 我是一所大学里的一名新生，

2. The outcome is still uncertain.
    结果仍不明朗.

3. Travellers on short trips to areas with water supplies of uncertain quality should avoid drinking tap-water, or untreated water from any other source.
    短途旅行到水质不保险的地区时，应避免饮用水龙头的水或未经处理任何其他来源的水。

4. At this altitude, the air is very thin and the weather is uncertain.
    在这样高度上，空气十分稀薄，气候变幻无常，

5. Sometimes you may feel uncertain about whether to give in to many of your children's requests.
    有时你也许会对自己是否要对孩子提出的许多要求作出让步感到没有把握。

6. It is an uncertain moment, a scary moment.
    这是个变幻莫测的时刻，

7. In the first picture, the bride and groom are facing, with uncertain smiles, a church filled with relatives and friends.
    在第一张照片上，新娘和新郎面对着挤满亲朋好友的教堂，脸上挂着几丝不定的微笑。