现在时

C It belongs to the present tense so it doesn't go with exact past adverbial.

事是过去的事，但本质是属于现在时，所以不能和明确的过去时间连用。

Alternating current is usually supplied to people's house at 50 cycles per second.

一般现在时是科技文章中最常见的时态，主要有三种用法。

Watson pondered for a minute and said, Astronomically, it tells me that there are millions of galaxies and potentially billions of planets. Astrologically, I observe that Saturn is in Leo. Horologically, I deduce that the time is approximately a quarter past three. Theologically, I can see the God is all powerful and that we are small and insignificant. Meteorologically, I suspect that we will have a beautiful day tomorrow.

华生沉思了片刻，说：从天文学的角度来说，拿说明天上有成千上万的星系，而且还可能有几十亿万颗行星；从占星学的角度来说，我观察大土星在狮子座上；从钟表学的角度来说，我估计现在时凌晨3：15；从神鞋的角度来说，我看到了神威浩大，而我们是那么的渺小而微不足道；从气象学的角度来说，我推测明天天气晴好，阳光明媚。

Although it has never been explained why a few individuals seem to be always inclined to do something wrong than anyone else, ordinary people have regarded（陈述一个事实用一般现在时就好了） the law as something that cannot be disobeyed and provide s them with the best

又是抽象词。我的理解是：法律给人们提供的是一种保障，而 best 作名词指最好的状态或部分，用的不对；此外，生活又是抽象名词，我们去享受生活或体验生活，生活怎么会带给我们什么？和法律带给我们的保障又有什么可比性呢？

2 A clear glass capillary tube is fixed vertically in a beaker.

例2的问题是时态不统一，一般现在时和一般过去时交替使用，给读者的感觉好象是这个实验是在过去和现在两个时空中完成的，这是不可思议的。

If John is our best runner, then I am Carl Lewis.

所以都用现在时。

It took Mr Wang half an hour to clean the bedroom.

可以用于一般现在时，一般过去式和一般将来时态。

He has painted Mr Berisha as a demagogue in charge of a deeply corrupt government, arguing that it is time for a change.

他将Berisha描述成一个管理着极度腐败的政府而且蛊惑人心的领导者，坚持主张现在时改变的时候了。

Mistake one: It is my vacation soon - obviously we should use future tense in this sentence.

一般现在时表达将来的意思很常见的，我不觉得只能在口语中用。

I don't have luch at home. They don't play basketball on the sportsground. Mr.Jimmy doesn't know French.

一般现在时一般现在时-表示将来在一些情况下，一般将来时能用来表示将来时。

The absorption and distribution of chromium were studied in ryeusing nutrient culture technique and pot experiment.

采用不同浓度K2CrO4(0，0.4，0.8和1.2 mmol/L)的Hoagland营养液处理黑麦幼苗，测定铬在黑麦体内的亚细胞分布、铬化学形态及不同部位的积累。

By analyzing theory foundation of mathematical morphology in the digital image processing, researching morphology arithmetic of the binary Image, discussing two basic forms for the least structure element: dilation and erosion.

通过分析数学形态学在图像中的理论基础，研究二值图像的形态分析算法，探讨最小结构元素的两种基本形态：膨胀和腐蚀；分析了数学形态学复杂算法的基本原理，把数学形态学的部分并行处理理念引入到家实际应用中。