将“老水车、驳船、矿灯、稻穗、路基”这几个形象、填入下列空缺处：

我是你河边上破旧的____，数百年来纺着疲惫的歌；我是你额上熏黑的____，照你在历史的隧洞里蜗行摸索；我是干瘪的____，是失修的____；是淤滩上的____  把纤绳深深勒进你的肩膊。

    In Chinese culture, people believe some numbers are lucky or unlucky. This is to see what Chinese character the number sounds like. For example, the Chinese word for the number 8 sounds like the word for “making a fortune”. So, people think it is a very lucky number. Some people spend a lot of money to have 8s in their phone numbers. The opening time of the Beijing Olympics began at 8:08 p.m. on August 8, 2008.

    The number 9 is also a lucky number. It is something to do with the emperors of China. There were nine dragons on emperors' robes(龙袍). Today, 9 often stands for “long lasting”. That's why close friends always use 99 or 999 to describe their friendship.

    So what's a “bad luck” number in China? It might be 4. Many Chinese people see 4 as a “bad luck” number. Because it sounds like the Chinese character for “death”.

    Because of this, many buildings don't have the fourth floor, and just call it the fifth floor. In Hong Kong, some buildings even don't have all floors numbered with 4, such as, 4、14、24、34 and all 40-49 floors. Some buildings also don't have the 13^th floor as 13 is an unlucky number in the West. Now a question for you: How many floors are actually there if a building's highest floor is numbered 50?

用化学用语表示

①两个氢气分子____  ②正二价的镁元素____．

用下列简单机械(如图），使重量同为G的物体都处于静止状态，其中用力最大的是(均不计摩擦)